MyBB Community Forums

I am using mybb from two months. I have edited themes files, header, index, etc

After upgrade will i able to keep the customization or i have to do it again?

my forum: http://funchit.com

Depends which upgrade you're referring to. If it's to another 1.4 version, they'll stay fine. If it was to 1.6, whenever it's out, you'd lose them, but you could make the changes again after quite quickly.