Categories in the inventory managment

Hi to all, hope on the open and helpful answers.

We have snacking production company and utilize Sage 50 Quantum Accounting for managing the process. Have tons of items in the inventory but can't arrange them in categories. By default the system switched off that option, I tried  4-5 ways from the knowlagebase to swith it on without any success. As I think the main issue is our old interface. Please help to apply categories into inventory.