I think BF has way too many menus, so here's a more comprehensive guide.
From the main menu, select (
From the next screen ("Multiplayer"), scroll down and select Gun Bench
From there, tap
to switch from Gun Bench to Character Customization
The first class you should see under the Operator tab is Swat, followed below by Undercover, Thieves and Bangers. You will want to customize each one of these, one at a time.
Starting with the Swat then, scroll to the right and select "CLOTH
" under "COLORS". A collor palette will appear on the right. Select whichever you want then back out (
). Do the same for the other types of characters above mentioned.
When you're done, press
to go to the Mechanic and proceed in the same manner as above described. When you are done changing all 16 characters, press
on your controller, then scroll down and select "Save and Quit".
Now, go back to Multiplayer, enter a quick match of your choice. The achievement should pop right away, as soon as it starts, after the loading screen.
If this solution helps you in any way, please leave a thumbs up to let me know. Thanks!