Getting logged out on cell phone

Everytime I access TPT in Safari on my cell phone, I need to log in. This just started happening. I know there is somewhere in Settings I need to go to fix this. Can somebody please help? thanks.

When you are logged out - then, when you click the Login link and are presented with the username/password login dialog: There is a checkbox underneath that says 'log me in automatically with each visit'.

If you check that box off, then complete login -- it should automatically log you in upon subsequent visits to the site.