Well I got it all wrong then.. so "Cancel (double-spend)"-increase fee and "OK" and that's it? What happens if I don't do that? It takes weeks / months to transfer?
We do not know the fee rate (sat/vbyte) that you used. What fee rate that you used?
Just visit
https://mempool.space/. You will see the fee priority in Sat/vbyte. On Electrum, you will see 'bump fee' or 'increase fee' when you click or right click on your transaction. Increase the fee to the l recommended fee on memepool.space.
Before making transaction next time, you can always check memepool.space.