You're not doing anything wrong here, it looks like a problem
with permissions on your Firefox profile. My first suggestion would
be to go to Applications > Utilities, open Disk Utility and run
the 'Repair Disk Permissions' on your main drive and see if that
If it doesn't please let me know and we can try to track down
the issue, it would be good to know which version of the main
1Password app you have installed too, you can check this via
1Password > About 1Password.