Thank you Cristian.

> I want to merge 2 categories into 1. I started changing each operation from
> category 1 to category 2 (right click --> move operation to...) but this
> takes a while...

You can also do this using multiple selection.

Well, I can select all operations, but then I can't find out how to move them all : right click considers only the operation upon which the mouse cursor is set.

>
> As I can "select all" operations from category 1, is there a smarter way to
> move them all to category 2 ?

Yes, there is [1]. Delete category 1 and you will be asked where do
you want to move the existing transactions.

Yes, this happens in most cases but for a reason I can't find out, I can't delete this particular category : "delete" is greyed. Any idea why ?

Hugo