How to Configure Expert Advisor Settings

Before you start

• An EA installed and attached to a chart — see the MT5 or MT4 install tutorial.
• The EA's documentation, which explains what each of its inputs does.
• A demo account for trying new settings.

What you'll learn

• Reopen an EA's properties at any time.
• Recognise the common inputs and the units they use.
• Save, load and reset settings with .set files.

Steps

1. 1

   Step 1: Open the EA's properties

   Click the chart the EA is attached to and press F7, or right-click the chart and choose Expert Advisors → Properties. Open the Inputs tab.

   Mark as done: Open the EA's properties
2. 2

   Step 2: Find the position-size setting

   Most EAs use either a fixed lot (for example 0.01) or risk-based sizing (a percentage of balance per trade). Start with the smallest size your account allows while you learn how the EA behaves.

   Settings that multiply lot size after a loss (martingale) or add positions as price moves against you (grid/averaging) concentrate risk in rare but severe losses. Make sure you understand them before changing their values.

   Mark as done: Find the position-size setting
3. 3

   Step 3: Check the units of stop-loss and take-profit

   Inputs may be in pips or in points. On a 5-digit EUR/USD quote, 1 pip = 10 points, so a stop-loss of "20" means very different distances depending on the unit. The documentation (or the input's name) should say which one is used.

   Mark as done: Check the units of stop-loss and take-profit
4. 4

   Step 4: Give each copy a unique magic number

   The magic number labels the trades an EA opens so it only manages its own. If you run the same EA on several charts, give each chart a different magic number unless the developer says otherwise.

   Mark as done: Give each copy a unique magic number
5. 5

   Step 5: Review filters and limits

   Many EAs also have:

   • A maximum spread — the EA won't open trades when the spread is wider.
   • Trading hours or session filters (check whether they use broker server time).
   • Slippage or maximum deviation for order execution.
   • Limits such as maximum open trades or a daily loss stop.

   Mark as done: Review filters and limits
6. 6

   Step 6: Save your settings as a .set file

   On the Inputs tab, click Save and give the file a descriptive name (for example eurusd-h1-demo.set). It's stored in the Presets folder. Load restores it later, and Reset returns every input to the developer's defaults.

   Mark as done: Save your settings as a .set file
7. 7

   Step 7: Apply and check the log

   Click OK. Most EAs re-initialise with the new values; the Experts tab (Ctrl+T) should show the EA reloading without errors.

   Mark as done: Apply and check the log

Troubleshooting

"Invalid volume" errors after changing the lot size

The size is below the broker's minimum, above its maximum, or not a multiple of its volume step. Check the symbol's Specification in Market Watch.

"Invalid stops" errors

The stop-loss or take-profit is inside the broker's minimum distance, or you entered pips where the EA expects points. Recheck the unit.

Settings are lost after restarting MetaTrader

Save a .set file, and save your chart layout as a profile or template so the EA and its settings come back together.