I had the same problem with new hearing aids just like yours, over the ear. I went to Universal last November and wondered how the hearing aids would work with their fast and bumpy rides.
I'm happy to say it went just fine. It was hot and sweaty when we were there, and I had no issues with my HA's at all. I just touched them to make sure they were secure before getting on the faster and rougher rides, and they were fine each time.
I do understand your anxiety with hearing aids since they are still new to you though.
Sometimes I just took them off and put them in their carrying case because the noise could get to be too loud at times on the attractions. So there's that option if you are worried about them. Just take them off for a while.
It will all be fine, so have fun!
They only time I ever worry about the hearing aids is when I go to take a shower. I make doubly sure that I took them off before showering, but that's it. It's so much nicer being able to hear what others are saying