It kind of looks like that, but the version shows as 3.8.8.
The Key looks just like that.
I always just use the default wallet.
I guess I could uninstall and reinstall.
A little worried about losing bitcoin, but if I use my seed, it should be ok, right?
The wallet (software) version is/can be different from your wallet FILE version.
Also : there's no reason to delete/uninstall anything really.
Here's what you should try, in my opinion;
1. You should import your seed first to see if you actually generate the right wallet, containing all of your bitcoins (it should! just to make sure!)
Once you imported your seed (with Restore -> "name your "new" wallet" -> "Standard Wallet -> I already have a seed")
2. You should go to Wallet -> Information, and see if the MPK is updated. (I haven't looked into this, so it might not change, even after "restoring"..)
3. If not, you need to generate a new wallet (new seed.) (You can choose between Legacy and Segwit. Legacy is 1.., and segwit are the newer bc1... address, which lets you save on transaction fees.)
4. Then, check if the MPK is correct in the new wallet. (Either xpubXXXXX for a legacy wallet and zpubXXXXX for Segwit
(Actually, you can't use Segwit for multisig as it'll generate a zpub instead of the required Zpub), so, stick to generating a new legacy wallet.
5. and then transfer all of your bitcoins to the new wallet. (You don't actually need to do this. You can also just use the xpub + master private key for your multisig operandi (?).)
Don't delete any wallet files, or even uninstall Electrum, as i don't think that's the issue here.
What i don't understand is why you necessarily want the xpub to be from the wallet (master private key) where your bitcoins from your p2pkh “wallet” are stored in. ..Convenience? It doesn’t seem convenient to me at all.
I haven't asked, and perhaps it is none of my business, but what are you planning on using Multisig for? Or, why you even want to “update” the master public key of your p2pkh wallet, as you can also just create a new multisig wallet just as easily.