I am working in Magento Project and my Client is complaining for logged out issue. Magento sets Cookie lifetime to 3600 seconds and after that it asks for Login again. So my client wants to increase Login Cookie time. If you are looking for the same than follow the below steps.
1) Login to Magento Admin Panel
2) Go to Configuration > Web > Session Cookie Management > Cookie Lifetime
3) Increase Cookie time and Save
4) You are Done.