@Cricktor I didn't follow a tutorial exactly, but I've read https://electrum.readthedocs.io/en/latest/multisig.html and https://bitcoinelectrum.com/creating-a-multisig-wallet and of course I made a mistake. I didn't consider the consequences of the "Enter cosigner seed" option.

Thank you for the reminder. I'll store the seeds in different locations and all public keys in multiple places.

@nc50lc
That's exactly what I mean. I'm glad I checked this (and asked about the confusion) before doing any valuable transactions.

That's true, and I think it would be a nice addition to the information dialog to show for which cosigners the current wallet can also sign the transaction.