Help with App Store!

Although I have jailbroke my iPhone, there is still some free apps I download from the app store.
The iPhone I am currently using was previously owned by my step mam (not relivant).
Its a 3GS 16gb OS 4.0.1 (am I wrong to believe this is the latest firmware with a STABLE jailbreak?)
For example I downloaded "Smurfs Village", when asked for a password it showed MY itunes account username therefore I entered my password and as expected it downloaded and installed perfectly.
The problem i'm experiancing is the update.
When I load the app store it says I have an available update for "Smurfs Village".
WheN I click update, it shows my step mams itunes account username therefore not being able to update ANY app I have downloaded.
I had already gone to the store settings and logged out of my step mams account and logged into my own before I downloaded it so why is it asking for HER password???

I tried iTunes on the PC and tried toupdate through there but NO apps were visible and it said no updates available.
I tried syncing the apps, it said it was backing it up then because I have no apps on the PC it decided to delete them all from my iPhone.
And once it had finished syncing it told me "iTunes could not backup the iPhone "RICKY" because the iPhone disconnected"
Afterwards I checked my iPhone same problems were occuring and it deleted all the apps I downloaded through installous but left the ones downloaded through app store.
Still they didnt show on iTunes.

I think thats everything lol

 

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