How to update apps on used mac
Bought a year old used iMac. I believe it came with apps like iPhoto, Garage Band and iMovie when it was purchased new. The App Store reminds me that there are updates available for these apps but I cannot download them because they are listed as being purchased by the original owner and require his password to update. How do I fix this? Do I trash the current apps and then repurchase using my Apple ID and password? Seems to me that if they came with the iMac, then I should be able to update without additional cost. Am I wrong?
iMac, OS X Mountain Lion (10.8.3)