No worries, changing the formula separator from semi-colon to comma is a quick and easy fix. Here's how you can do it:

1. Open Excel and click on the "File" tab in the top left corner.
2. Click on "Options" at the bottom of the left-hand menu.
3. In the Excel Options window, click on "Advanced" in the left-hand menu.
4. Scroll down until you see the "General" section.
5. Look for the "List separator" option and change the semi-colon to a comma.
6. Click "OK" to save your changes.

That's it! Now, when you enter formulas in Excel, you can use a comma instead of a semi-colon as the separator. This should make it easier for you to work with Excel formulas. If you have any other questions or concerns, feel free to ask.