(new customer) Can my family and I switch phones?

Yesterday my family and I went to T mobile and became customers and got new phones through a Go5g plan for 3. We all wanted different color phones but the guys at the T mobile never told us if we wanted to choose colors and just gave us black phones and I Asked if we could order the colors online and they said that's we couldn't. My family wanted an specific color. Silly question but is there a way to switch phones or return them and use my own phone? Also the guys at the store never asked us if we wanted different versions of the phones. We all wanted more storage.