Add threads to your favorites list:-
Option to view Favorites list:-
How Favorites list looks like:-
1.Use image files of jpg or png extension which is 80 by 80 pixels (File extension is my personal recommendation)
2.Be sure that "Use Custom Avatar" option is selected.
3.After browsing your avatar,when u click on "save changes" option,be sure that your avatar is visible on that current page.
If,it is not visible, click "save changes" option again and again till u see see it on the current page.Now,if it is visible,then click "edit avatar" option again which is below settings and options on the left hand side of the page.If u are able to see your avatar at this time,then u are done,unless repeat the same process again.