choose: Specify avatar by URL
in case it doesn't choose it for you, make sure it says "no pic" from the avatars drop down selections box next to where you paste your avatar url. if it doesn't click on "no pic".
paste your image/avatar url from post image after you have copied it into your clip board.
looks like this:
https://s9.postimg.cc/yourimage.gifneeds to be around 80x 80 for the size. if it's too big it won't allow it. so try to edit it at post image by resizing it to 80x80 and then use the resized image as i pointed out above.
i could help out anyone who is stuck when i get some time for it. just pm me what you want posted and i have to login with your id to paste it into your avatar profile.
if your on a pc you can use their app to make it easier to do like i do.