First before doing anything, you should install the latest release of 5.21 (you may already have 5.21 but you should download it and check if it is exaclty the same). It did download the latest version and it has some improvements around the personal albums and member gallery.
Personal albums is a way for the user to regroup images.
Member gallery will normally display image that the user uploaded to your main category or directly to the member gallery.
In the admin, you can check an option to make sure that user that upload pictures to personal albums are also displayed in the member gallery.
It may look confusing first but if you get the latest upgrade, it will make more sense...