Ah, I get it. So, they can spend my coins that where already in the wallet at the time of the backup / or before I changed the password (that part I didn't get straight), but they cannot spend the new coins that arrive there.

Thank you. The old wallet was hacked actually and they took some coins :/ ... but I have a miner still sending coins there (I'm going to change it after a few blocks) and I was afraid they could also get my new stuff.

Thanks again.