I just use Watch Face Studio to make watch faces for myself (not the Play Store).
The problem I have is that in order to have multiple custom faces on my watch, they need different Package names.
In order to do that, I need the keystore password, key alias, and key password.
At some point, I may have done this, but I didn’t save anything.
A few posts mentioned needing an author certificate, but I have no clue how to generate one.
I’d appreciate any help you could offer
Simply create a new Keystore since you are not uploading to playstore it does not matter. Remember the password and don’t use any non-english characters and avoid non alphanumeric characters. Write it down for next time. I use the same password for the keystore and keystore alias.
For Galaxy Store apps you create an Author Certificate which tells Samsung who you are so no one else can replace your app with something that is something else. And a distributor certificate which tells your watch that it is safe to run that on the watch.
For Play Store apps (Watch Face Studio) you create a keystore which is basically the Author and Distributor certificate in one.
Samsung Developer Relations