Sure, I can help you with that! Here are the steps to change the unit of measure from cm to inches in the Format Picture size tab in Excel:

1. Right-click on the picture you want to format and select "Format Picture" from the drop-down menu.
2. In the Format Picture pane that appears on the right-hand side of the screen, click on the "Size & Properties" tab.
3. Under the "Size" section, you should see two fields for "Width" and "Height" with the current unit of measure displayed (likely cm).
4. Click on the drop-down menu next to the unit of measure and select "in" for inches.
5. The values in the "Width" and "Height" fields should now be displayed in inches instead of cm.

That's it! You've successfully changed the unit of measure from cm to inches in the Format Picture size tab in Excel. Let me know if you have any other questions or if there's anything else I can help you with.