What login are you referring too?
With most of the session logins they are limited to 20 minutes by default, when application specific time-outs are not specified, in the Coldfusion Administrator. Increasing this time may extend the time it takes to log you out, but this will apply to all sessions through out that don't have the time specified so make sure it doesnt impact somewhere else first.
Take a look at Configuring and using session variables - ColdFusion, English documentation - Adobe Learning Resources for more info
CF10 Requires too frequent login. How to extend the time between logins. Worked fine in CF8
<!--- With this code, ColdFusion will log user out if he has been inactive for 1200 seconds --->