In light of some of the recent login discussions here is one alternative; connect securely without having to enter a user name and password into Radmin Viewer. This does not involve saving user names and passwords but it does rely on your Windows logon credentials.
The bottom line is that the same Windows accounts and credentials (user names and passwords) need to exist on both machines and you need to connect using Windows authentication. Here it is step-by-step:
1) On the remote PC (running Radmin Server) configure Radmin Server to use Windows Authentication.
2) On the remote PC set up a user account with the same user name and password as the one you will use on the local PC (running Radmin Viewer).
3) On the remote PC add that user under Radmin Server permissions.
4) On the local PC open the Viewer properties for your connection. Under General / Windows Security make sure that "Do not use current user in windows authentication" is not checked.
5) You should now be able to connect directly without re-entering your Windows credentials.
6) If you want to connect directly to a PC using a shortcut you can use something like this as your shortcut target:
... where 188.8.131.52 is the IP you'd normally use. See the Radmin Viewer help file for the full command-line syntax.
So if you choose you can connect to another PC securely with a single click. Note that this is not auto logon by saving your user name and password. It simply configures Radmin to use the Windows credentials that you've already supplied.
For those living in impenetrable bunkers I'm guessing it should work with Windows users set up without passwords