Hello,
to my knowledge you have to delete your preference file. Resetting the preferences will restore Photoshop settings to factory defaults!
For a MAC I found this solution: Command+Option+Shift. Then, click "Yes" to the message, "Delete the Adobe Photoshop Settings file.
In Window's Explorer you have to set options to "View Hidden Files and Folders" to display the "Preference file".
Hans-Günter