i currently own a domain --> accessvision.net
and i pointed the frihost nameservers (accessvision.us.to)
but when i visit accessvision.net,
the address changes to accessvision.us.to
Put a slash at the end when you go to the site.
If you type in a directory name without a slash at the end, you'll be redirected to the old URL (with a slash on the end).
Otherwise, ask the admins to change your main domain to accessvision.net, and then add accessvision.us.to as a parked domain (so people going to your old URL can still access it)
Yes that should be the best option, then people can still go if they do not have the new link and once they find out about the new link they can use that. But i would make your new domain the main domain.