Besides the issue you are encountering the biggest issue with free forum hosts is they will usually hold the database hostage. If you ever want to move the site you'll be lucky to get it by paying a ransom and in many cases never.
Instead get your own domain and hosting, might cost you $5 to $10 per month after the initial offer expires. You can download install phpBB forum software for free.
https://www.phpbb.com/downloads/
Little bit of learning curve but if you know how to read it's not that difficult and of course if you need help it's readily available in their forum or elsewhere. Everything is in your control, you'd have to have some pretty radical stuff going on for the host to interfere and there is plenty of hosts.... If for any reason you lose the host you simply upload the files and database to another host and you are right back in business where you left off.