"You can change your mind."

It is possible to say 'Onun fikrini değiştirebilirsin.' (You can change his/her idea.) but it's not possible to say 'Senin fikrini değiştirebilirsin'. It really sounds even worse than saying 'I see me.' instead of 'I see myself' in English. In other words the object cannot include the same pronoun with the subject.

So if you want to emphasize 'your' you can only say 'Kendi fikrini değiştirebilirsin' which translates to 'You can change your own mind.'