To change underwear, do the same as you did for skin tone, except this time, you must click on body groups. From there, you can change the skin color of the Inkling and/or Octoling. To change the skin tone, you must right click on the Inkling while holding your context key (c by default) and find the 'skins' icon. If you do not have it, you can download it via the Steam Workshop. To change the color of an Inkling/Octoling, use the TF2 paint tool.
