Hi, thanks for your advise! I think that should be manageable since there is one more Computer. It is running a Windows system.
"extracting the private key" - do you mean that I have to put the wallet.dat backup from this computer to another and exchange the wallet.dat file with the one in the bitcoin folder?
I just want to be sure that I wont do any mistakes this time
Yup. Install Bitcoin Core, run it once and shut down and go to the data directory (usually is at %appdata%/Bitcoin). Just replace the wallet.dat and reopen Core. You can just use the commands to dump the private key out."extracting the private key" - do you mean that I have to put the wallet.dat backup from this computer to another and exchange the wallet.dat file with the one in the bitcoin folder?
I just want to be sure that I wont do any mistakes this time
Don't import it into Electrum preferably. Sweep it and you can just store the seed as a backup.