Thanks for all the answers!

And I guess you're right, I just have to read all terms. Although I always have the feeling I'm the only fool reading the tiny letters. That will take quite some time, as I wanted to try whether it is possible to benefit from the price differences between exchanges. So I wanted to register at least 5 or so.

Do you think it would be possible to benefit from price differences between exchanges? Or can I better save myself the time to try this?