Hello There, I have rather foolishly used the tax code (20% ECS) in most of my expenses instead of the (Standard S 20%) Is there a way I can REPLACE ALL?

For now, we don't have an option to edit multiple transactions at once, Luke.

You'll need to update the expense transactions one at a time:

1. Select Expenses on the left menu and go to the Expenses tab.
2. Click the Filter button and select Expense in the Type field. 
3. Enter necessary filters and click Apply.
4. Update the expense transaction and click Save.

Fill me in if you need anything else. Have a great day!