Comment 8 for bug 152504

When and why do you get asked for a password?

Did you use the "Goto Server" which opens a dialog asking for a remote server and login? Then login and password (will be asked for in a later step) must be either of "root" on the server or of a user who is in the "lpadmin" group on the server.

If you set up a local print queue (you did not use "Goto Server") and you are a user in the "lpadmin" group, you will never get asked for a password, also not for the "Server Settings". Can you check whether you are actually in the "lpadmin" group in /etc/group (and add yourself if needed)? Do you get asked for only the password or for login and password? In the latter case enter the login and password of a user in the "lpadmin" group. If you are asked only for the password, you must start system-config-printer as a user in the "lpadmin" group.