Have I mentioned you're my hero? 

Thank you SO much!

@media screen and (max-width:480px) {
    #wpforo #wpforo-wrap {
       padding:20px 5px;
    }
}

Then use mobile browsers private session to check. Mobile browsers do hard cache so you may not see the change. Use other devices or browsers to avoid caches on mobile.

While I have you here, do you have any advice/code I can use to adjust the padding on the mobile version of the forums? While I don't want the posts to go all the way to the edge of the screen, the padding is a bit much as it is.

This is what I have in the Forums->Settings->Style CSS section (it may be something I messed up):

#wpforo #wpforo-wrap {
font-size: 13px; width: 100%; padding:20px 40px; margin:0px;
}
#wpforo #wpforo-wrap .wpfl-1 .wpforo-category {margin:10px 0px -1px 0px;}
#wpforo #wpforo-wrap .wpfl-1 .wpforo-forum {margin:0px 0px 2px 0px;}
#wpforo #wpforo-wrap #wpforo-menu { background-color:#777777; }
.fa-lightbulb:before {
content: "\f072";
font-weight: 600;
}

@media screen and (max-width:480px) {
#wpforo #wpforo-wrap .wpforo-post .wpf-right ul li {
margin: 2px 0px 2px 7px;
}
}

Here's a screenshot:

Unfortunately, the reason is that your website is hosted on wordpress.com. I really don't know if there is a way to stop caching  saving images in wordpress.com CDN system. You should contact to wordpress.com support. They may provide some code to stop caching avatars.

I appreciate your time!

This comes from wordpress.com. Where is located your website? Maybe you use wordpress.com system and it's automaticaly saved in wp.com CDN systme. Or maybe you use some WordPress solutions like Jetpack or so.

wpForo doesn't have such problem, this is caused by your plugins. You have some plugin or a caching solution which automatically stores  and caches avatars in io.wp.com CDN. You should know what is this and you should try to find some option in that plugin to stop caching avatars. This issue can not be fixed from wpForo side, this is not wpForo issue.

https://wpforo.com/wp-content/uploads/2018/09/wpForo-avatar-changing-issue-cache-1.png

My users and I are having issues changing our avatar after the first time. It's like once the avatar is changed it can't be undone. Now I've tried testing it, and sometimes I can get it to change, but not consistently, and maybe only once out of 20 times. I have tried deleting caches and everything. Is there something I and my users are both missing? Is there a code I can put in functions.php to rectify this issue? 

The website is rotarytoairlinegroup.org and I believe your team already has a login there if you'd like to test it out. 

Thank you so much for your help.