MyBB Community Forums

Hi
i setup my mybb forums with this addres : alteriw.ir/forums
but after 2 month i buy new domain (plusgamer.ir )and now i changed my
forums domain to plusgamer.ir (from General Configuration in acp)
but now i have big problim with login?!!
i cannot login to my forums what can i do to set completely my new domain to my forums?!

thank you.

Edit:
Solved sorry i forget to change Cookie Domain also

But i want to change my question:

i want change all old link (alteriw.ir) to new one (plusgamer).
i think the easy way is sql query.
so how i can do that?!