Done! I recalled I did this in another sheet.

I added a new tab ‘non-fixed categories’ where you can add, delete or modify the existing non-fixed categories. These fields in tab ‘non-fixed categories’ will be pulled in two places:
- To the Overview tab via an ArrayFormula in field B24,
- And to all the dropdown fields in all the other tabs where you can write down your individual expenses.

Now if we need to make an adjustment, we only have to make it once. Hope this is helpful. Thanks again for sharing your idea!