How to change MT5 expert advisor inputs: where they live, when changes apply and how to save a preset

How to change MT5 expert advisor inputs

To change MT5 expert advisor inputs, open the EA's properties window from the chart it is running on, go to the Inputs tab, double-click the value you want to edit, then click OK. MetaTrader 5 restarts the EA on that chart with the new values right away. You do not need to remove and reattach it. Before you test the configuration later, save it with the Save button on the same tab.

This guide covers the mechanics. It explains where the input parameters live, what actually happens inside the terminal when you apply a change, and how to keep a clean record of each configuration. If you want to know what common inputs like lot size or magic number mean, the guide to MT5 expert advisor settings for beginners covers that.

Where EA inputs live in MetaTrader 5

Inputs belong to one EA instance on one chart. If the same EA runs on EURUSD H1 and on a broker's US index CFD on M5, each chart has its own set of input values. Editing one does not touch the other.

To reach the EA properties on a chart that already runs an EA:

1. Right-click the chart and open Expert List (Ctrl+E is the usual shortcut). Select the EA and click Properties.
2. Or double-click the EA name shown in the top-right corner of the chart. Depending on your build, this opens the same window.
3. When you first drag an EA from the Navigator onto a chart, the same properties window opens automatically before the EA starts.

The window has several tabs. Common holds permissions such as allowing algo trading for this EA. Dependencies lists any libraries or indicators the EA loads. Inputs holds the input parameters. The developer controls the Inputs tab completely: only variables declared as inputs in the code appear there. If a setting you expect is missing, the EA does not expose it. Check the EA's documentation rather than looking for a hidden menu.

MetaQuotes describes the properties window and the algo trading permissions in the MetaTrader 5 algorithmic trading help.

Reading the Inputs tab

Each row shows a variable name and a value. Some EAs use a readable label instead of the raw code name. Values come in a few types:

• Numbers, such as a lot size of 0.10 or a stop distance in points.
• True or false switches, such as enabling a trailing stop.
• Dropdown lists (enumerations), such as a timeframe or a lot sizing mode.
• Text fields, such as a trade comment.

Double-click a value to edit it. For dropdowns, pick an option from the list. Units are the most common source of error. A stop of 200 can mean 200 points, 20 pips on a 5-digit EURUSD quote, or something else if the developer used their own unit. Confirm the unit in the documentation before you trust a number.

How changes take effect

When you click OK after editing inputs on a running EA, MetaTrader 5 does not hot-swap the values. It deinitializes the EA and initializes it again with the new parameters. In practice, this has several consequences you should plan for.

What resets and what stays

• Internal memory resets. Counters, flags and anything else the EA held in memory start from zero unless the developer saves that state somewhere persistent. Examples include a daily trade counter or a "trade already taken this session" flag.
• Open positions and pending orders stay. Reinitializing the EA does not close trades. Whether the restarted EA recognizes and manages them depends on how it was coded, usually through the magic number and symbol.
• Other charts are untouched. Only the instance you edited restarts.

The same reinitialization also happens when you change the chart's symbol or timeframe, so treat those actions with the same care.

A safe sequence for changing inputs on a live or demo account

1. Check the Trade tab for open positions and pending orders from this EA.
2. Decide whether you want the change applied while those positions are open. If the EA might not reattach to them correctly, or if you are changing the magic number, wait until the EA is flat.
3. Save the current configuration first (see the next section), so you can return to it.
4. Edit the inputs and click OK.
5. Open the Experts tab in the Toolbox and read the messages. Most EAs print an initialization message, and errors such as invalid parameter values usually show up here.
6. Confirm the smiley or active icon is visible in the chart corner and that algo trading is enabled in the terminal toolbar.

Changing the magic number on an EA with open trades deserves extra caution. Many EAs only manage orders that carry their own magic number. A new value can leave existing positions unmanaged.

How to save an EA preset

A preset is a .set file that stores the values from the Inputs tab. Saving one gives you an exact, reloadable record of a configuration. This matters when you compare results between versions of your settings.

Saving from a chart

1. Open the EA properties and go to the Inputs tab.
2. Click Save.
3. Give the file a descriptive name, for example EURUSD_H1_risk05_v2.set. Include the symbol, timeframe and something that identifies the change.
4. Note the folder the save dialog opens in. It sits inside the terminal's data folder, which you can reach through File > Open Data Folder.

To restore it later, use Load on the same tab. For a full walkthrough of loading presets, including how to check that a file matches your EA version, see how to load an MT5 set file.

Saving from the Strategy Tester

The Strategy Tester has its own Inputs tab. Right-click the input list to load or save a .set file there. You can save a live configuration from the chart and load it into the tester, so the backtest uses exactly the same values. If you optimize, the tester inputs also hold start, step and stop values for each parameter. The MetaTrader 5 Strategy Tester help documents these fields. For reading the report after a run, see how to test an expert advisor in MT5.

Templates and profiles also store inputs

If you save a chart template or a profile while an EA is attached, MetaTrader 5 stores the EA with its current inputs. Applying that template to another chart attaches the EA with the same values. This is convenient, but it can also attach an EA you did not intend to run. MetaQuotes explains templates and profiles in its charts help section. Use .set files as your main record of settings, and use templates for layout.

Keeping configurations testable

A preset is only useful if you can tell later what it was for. A few habits help:

• Change one thing at a time. If you edit risk, stop distance and session filter together, you cannot tell which change moved the results.
• Keep a short log. Next to each .set file, record the EA version, broker, symbol, timeframe and date. Broker symbol suffixes, for example EURUSD versus EURUSD.r, can matter if the EA filters by symbol.
• Test before deploying. Load the new preset in the Strategy Tester, then run it on a demo account before using it live.
• Keep the original vendor preset untouched. Save your edits under new names so you can always return to the baseline.

If you would rather start from an EA whose inputs are documented and that ships with ready set files, the MT5 expert advisor page lists the parameters and supplied presets, so you can see what each input controls before you change anything.

Conclusion

Inputs live in the Inputs tab of each EA instance's properties window. Clicking OK restarts that instance with the new values, which resets internal memory but leaves open trades in place. Save a .set file before and after each change, name it clearly, and load the same file into the Strategy Tester so your tests match what runs on the chart. Treat every change as a new configuration to verify, not as a quick tweak. Automated trading carries real risk, and no input combination guarantees any result.

FAQ

Why are some inputs grayed out or impossible to edit?

Some EAs only allow certain values to be changed in the Strategy Tester, or they lock parameters on purpose. If an input cannot be edited, check the developer's documentation. Its behavior is defined in the EA code, not by a terminal setting.

Can I change inputs while the market is closed?

Yes. The EA reinitializes immediately, but it usually acts only when new ticks arrive. Check the Experts tab for initialization messages to confirm the new values were accepted.

Will a .set file from another EA work on mine?

Only if the input names match. MetaTrader 5 maps values by parameter name, so mismatched or renamed inputs keep their defaults. Always review the Inputs tab after loading a file from another source.

Does the Reset button delete my saved presets?

No. Reset returns the inputs in the open window to the EA's default values. Saved .set files on disk are not affected.

Do I need to restart MetaTrader 5 after changing inputs?

No. Clicking OK in the properties window applies the change to that chart's EA instance. A terminal restart is not required.

If you want an automated strategy with documented inputs and supplied presets to test on a demo account, see the MT5 expert advisor available at SierraOnShop.