When that happen to me i just sign uout and sign in again
At the top right there should be three bars, press it. After that press settings and upload your pfp
If you scroll up to the top there should be a couple buttons/icons. Press the one with three lines then press settings. You should be able to upload a picture there
In mangago? Just go to your homepage
I mean settings dear
Helloooo I have a album pic describing how to do it
http://www.mangago.me/home/photo/9342067/
Thank you ❣
Helpp