How can I select a picture as my avatar/ profile picture?

To set a picture as your avatar/profile picture, go to the tab “Me” at the bottom of the bar, select “My photos”, choose one and then click on “Add to thumbnail” at the top right next to the three dots.

Please note that only pictures from the public gallery can be used as thumbnails. In addition, the picture must show your person and not an object or meme etc.