Q: Updating apps on my Macbook Pro, I'm the only user.....

Which apps specifically?

I suspected as much.

The iLife apps come free on a new Mac. But you need to make them part of your Mac App Store account in order to be able to update them. As part of setting up a new Mac, and before using even one of the three apps, you need to sign into your Apple ID for your Mac App Store account, go to the Purchases pane and accept the three apps. If you did not, but you use even one of the apps, then according to the Terms of Use for these apps, they do not become associated with your account, they cannot be installed on any other Mac that you own or control and they can never be updated.