Facebook Restricted Posts

I posted something on Facebook that I marked all Friends except. Now when I try to remove them it does not save my changes. For future posts I select to share with friends but friends can't share my posts unless I make them public, which I do not want to do. I want to limit it to all friends. Does anyone know how to save my changes of removing restricted friends? I tried on my iPhone and computer. Both with no luck. It's driving me crazy! Thank you!!!