How can I change authentication session timeout?

There are two settings:

1. Settings -> Admin -> Session expires (in minutes) - for Admin Area 
2. Settings -> Knowledgebase -> Session expires (in minutes) - for Public Area

Set it to the required value in minutes.
If you don't want the session to timeout at all, set these values to 0.  Your session should remain valid until you close your browser.

If it does not work as expected check the following values in your php settings.

1. session.cookie_lifetime (Default: 0)
   - session.cookie_lifetime specifies the lifetime of the cookie in seconds which is sent to the browser.
   - a value of 0 means "until the browser is closed"
2. session.gc_maxlifetime (Default: 1440)
   - session.gc_maxlifetime specifies the number of seconds after which data will be seen as 'garbage' and cleaned up.
   - garbage collection occurs during session start.

Tip:

• Do not forget to restart web server if you change php settings.