The pref file @JakobP is talking about is located in the Preferences folder. To locate it, try this:
In the Finder, choose Go > Go to Folder from the menu.
Type ~/Library/Preferences in the "Go to the folder" field.
Press the Go button.
the pref file is named com.apple.logic.pro.cs
Note: Type the path exactly as described, including the ~(tilde) -----> ~/Library/Preferences