Part of the problem is no or very few new members coming and the inevitable drop off of existing members—I have not seen Phemanderac post for years now and he was a good poster, high quality posts.
Cleaning up the front page as I have suggested might help to get visitors to join.
I think a dedicated server is extravagant—and if it goes down in the middle of the night here there is no one to tell Hostgator about it. With a shared server plenty other website Admins will be screaming to Hostgator, some in the same or adjacent time zones to it—i.e. would be screaming to Hostgator during our night.
Transferring from YABB to an SQL based platform would do the most good, going by what FD said about it. Be a nightmare to export/import all the data (posts, avatars, PMs, passwords, user groups etc) from YABB to another platform unless this is done by the host. Not sure what platform allows for MRBs, phpBB3 doesn’t, really, (use Forum Moderator functions?) Then move to a better host than hostgator.
phpBB3 will alllow Forum Moderators to be appointed—some permissions for this role are global so, like here, a Forum/MRB Mod will not be able to ban members from his or her board.
Members will have problems posting YouTubes and other media for people on Windoze10. Well, not posting but members using W10 won’t be able to see them.