It sounds like your Excel settings may be set to manual calculation mode, which means that formulas will not automatically recalculate when the underlying data changes. Here's how you can change your settings to automatic calculation mode:

1. Click on the "File" tab in the ribbon at the top of the screen.
2. Click on "Options" in the left-hand menu.
3. In the Excel Options dialog box, click on "Formulas" in the left-hand menu.
4. Under "Calculation options", make sure that "Automatic" is selected.
5. Click "OK" to save your changes.

Once you've changed your settings to automatic calculation mode, your should recalculate automatically when the underlying data changes. If you're still having trouble, you can try pressing the "F9" key to force a recalculation of all formulas in the sheet.