Q:

Do I wait or do I have to do something about it?

Nooby question here, I payed/sent an amount and it failed somehow, so I tried again and again. 
I checked their website and it´s all "failed" or incomplete. But is has a checkmark(sent) on Electrum. This was saturday, today is monday.
Now my question is, do I just wait and the BTC will comeback, or should I do something so it isn´t floating around?
Thanks in advance, 
Alain 
PS: Print so you have more details. 
https://gyazo.com/41e1f54c1bb11d1739e6a8da3664911b

A:

do I just wait and the BTC will comeback

No, the transaction be13...5f1b is complete and 0.00361861 BTC (about EUR 18.86 at time of writing) has been sent to address 1Exq...qoPf 
Nothing is going to come back just by waiting
The transaction, like all confirmed Bitcoin transactions, is final and irreversible.

should I do something so it isn´t floating around?

It isn't floating around. It has been moved to address 1Exq...qoPf. It can be spent by whoever has the private-keys from which that address was derived.

I payed/sent an amount and it failed somehow

This is an issue with whatever software/website is showing the "failed" message - you should ask the owner of that website (or developer of that software).

