Thanks a lot, Macropod!
I've got another question, though. Unfortunately I'm absolutely new on macros...

I copied the macro from the template you posted in the beginning. Then I copied the box twice, because I need two drop-down boxes next to each other in my template (that didn't work, the second box triggered a change under the first box). I want the two drop-down boxes to work individually. The output shall appear right under the box (just like in the template you posted). How do I have to change the macro/ What shall I do?

Hope my question is sufficiently precise...

I'd be super grateful for any help!

Regards,
Tim