imovie updates.

I was using my ex itunes account, however last year i got my own account and my new macbook pro and everything works great...except the imovie updates. Every time i wanna update it, my ex account name appears on the window and obviusly I dont know his password. This is very confuse for me. I dont understand why the other apps ask me the password for my actual account but imovie still ask me for the older one.

Please help me. I deleted the app but if I wanna it back I have to pay $200MN.

is there any other way to get my imovie update from my working account?

thank you