Cannot change primary weapon of teammates

[ozunasawai4]

On Xbox... When I go to the menu and select teammates and pick a particular teammate, it shows their weapon in the lower right corner. When I click on the weapon with the 'A' button it brings up a picture of them holding their weapon. But the only option on screen is to hit 'B' for cancel and below that it says "Weapons: 0". How do I get other weapons in their inventory or somehow to them so they can replace their primary weapon if I do not like it?