Sure, I can help you with that! Here are the steps to change the font size of the formula bar in Excel:

1. Open Excel and click on the "File" tab in the top left corner.
2. Click on "Options" in the left-hand menu.
3. In the Excel Options window, click on "General" in the left-hand menu.
4. Under "User Interface options", you will see a drop-down menu for "Font size". Click on the drop-down menu and select the font size you want for the formula bar.
5. Click "OK" to save your changes.

That's it! The font size of the formula bar should now be larger and easier to read. If you want to change the font size of other elements in Excel, such as the column headers or row numbers, you can do so in the same "General" options menu.