We just moved from a dedicated server to a managed server at df.eu (domainfactory) and therefore had to freshly create all our users on the new system.
Checking the config defaults of these users after first login, the "Refresh" setting under Preferences/User_Interface was by default set to "never". When this setting is manually changed within Roundcube to "every 1 minute(s)" and being saved by clicking the Save button, it does indeed first look as if it would have been saved. But if you later look again at the User Interface page (after you checked all other pages such as "Mailbox view" etc.), Refresh is still set to "never". You need to change and save it a second time.
All other settings of that page (Language, Time zone etc.) are correctly saved at first attempt. Even the option "every 60 minute(s)" of the Refresh item is correctly saved at the first attempt, just not the option "every 1 minute(s)". (Well, to be honest, I didn't check all options, just "1" and "60".)
This applies to 0.9.1 [GIT 20130602.1444] with classic skin, didn't check 1.0-git (yet).
Cheers,
Michael Heydekamp Co-Admin freexp.de Düsseldorf/Germany