You can copy the following directory:
Windows XP and earlier:
C:\Program Files\PLSQL Developer\Preferences\
Windows Vista and later:
%APPDATA%\ PLSQL Developer\Preferences\
(e.g: C:\Users\\AppData\Roaming\PLSQL Developer\Preferences\)
You can also copy settings like desktop layout, recent files, and so on by exporting and importing the following registry section:
HKEY_CURRENT_USER\Software\Allround Automations\PL/SQL Developer