Username, passwords and groups together with the additional parameters are managed in 4 tabs:
If you don't want to use the default password policy (see Setting a Password Policy), you can define in this tab a different password policy, marking "Use the policy below" and setting the appropriate elements. You may also select your own set of symbols to use when generating a password containing them. You may also set this list for the whole database via "Manage → Options → Password Policy" tab and override it for specific entries.