This is the Avatar path: /wp-content/uploads/wpforo/avatars/

By the way, where do the uploaded avatars go? I can't find it in attachments. In case I want to delete some avatars, I don't see a way to do that.

I have checked the hook, and it works correct, in the screenshot you provided is written syntax error, which means that there is a missing symbol, wrong symbol, wrong name etc. but not the hook which Robert has provided. The hook works correct.

The issue comes that You hadn't added the code properly, or made changes in the PHP file.

Yes, the hook had been added. You can use it and increase the max avatar size using the hook code below. Put it in the functions.php file of your current active WordPress theme or install the Code Snippets plugin and insert the code as a new code snippet. It'll increase the max avatar size to 5MB, you can change it in the code:

add_filter('wpforo_avatar_upload_max_filesize', function ($size){
   return (5*1048576); //5MB
});

I'm new here but interested in the max. size avatar image upload matter. Some of my uers have had problems trying to upload their image. Has anything been done in the last 3 years ? I can't find anything on my back end panel...

Thank you,

B.

Sorry for the delay. 

We'll add a new filter wpforo_avatar_upload_max_filesize in next version release. You'll be able to change the avatar upload size, and set it as you like. For now, wpForo doesn't allow to upload the images bigger than 2MB. Please wait for the next update.