In the GUI, at the list of updates there should normally be a blue update button. If you don’t see it, back to the terminal and run sudo apt upgrade to install those 96 packages.
You said you’ve had the phone for several months, so it would be useful to know which repository it’s on, amber (older) or byzantium (latest). Can you go to the store app again, click on the hamburger menu at top, then Software Repositories, and report here which it is?
Don’t worry. If it’s mistyped, it will be rejected as an unknown command.