On my iPhone 5s about 4 months old, everytime I open a contact on whattsapp I cant seem to go back to anything else but to "invite to whattsapp" I have to reboot the phone. Please help.
You should see "All Contacts" with an arrow at the top of the page, left side, when you look at a contact. When you tap this, you should return to the contacts list, and at the bottom, you'll see Favorites, Status, ... again.