Overview: There are 3 basic steps which will help you to enable the OAF page personalization option in Oracle R12 Application.
Navigation: System Administrator > Profile > System
Step1: FND: Personalization Region Link Enabled -> Yes
Step2: Personalize Self-Service Defn -> Yes
Step3: Disable Self-Service Personal -> No
Result: below screen shows that your ‘personalize page’ option is enabled.