Mutliple Choice: Grey mouseover

Hey everyone

I just started to use Adobe Captivate for the first time. Now I reached a Problem I can't solve myself and I also can't find anything that would help with Google.

Maybe you guys can help me:

I'm trying to make a Multiple Choice Quizz but there's a kinda ugly Grey rectangle behind the answers when you go with the mouse over those answers. Is there any possibility to delete that?

Thank you already in advance!