32bit ???

I just downloaded the game from website but it still running for 32bit. although my Window is 64bit system.
how to change/fix this ?

If you downloaded TBC or wotlk, there is no 64 bit client for those expansions.

Then I guess my memory error msg is from something else.. and that`s because its says that the game can not find enough memory to support it .. ;/ and I though this would be the thing to fix it..

You can make Wow.exe large address aware: https://www.techpowerup.com/forums/t...-aware.112556/

That way it can use more memory and you should not see such error messages anymore. Without it WoW client can only use 2 GB of memory and that can be too low at ultra settings and with some addons. Warmanes wotlk client with WoD character models also causes this problem if you don't make Wow.exe large address aware.