Although I have heard about an option to Encrypt ALL files, which I think may re-encrypt all the files with a new password, but I haven't tested this.
If you want ALL the files to be in a single password encrypted archive you will need to extract , add & encrypt in order to encrypt them all.which was the purpose of me asking question because I did not want to do this step.
7zip encrypts the contents of an archive that are present when you apply the encryption.
Adding files to a password encrypted archive create a 2nd archive, which may or may not be encrypted depending on whether encrypt files was selected in the Add Files dialog box.
If you want ALL the files to be in a single password encrypted archive you will need to extract , add & encrypt in order to encrypt them all.
Although I have heard about an option to Encrypt ALL files, which I think may re-encrypt all the files with a new password, but I haven't tested this.
Hope this helps
Colin