No matter if I select a new tattoo option, or deselect the current one, nothing changes. I tried saving a new tattoo option, tried refreshing, and I have cleared my cache recently. It's just not working.

I'm not sure if this is intentional or not, but I noticed with outfits that seem to have their own tattoo markings, like the Seductive Demon's Form, Witch Doctor's Outfit, or Kobold's Hunter outfit, it'll override any selected tattoo in the base section since the outfit worn already has a tattoo design.
Every time I've tried to make an avatar that has a tattoo selected from the base designs while wearing an outfit that has its own tattoo markings, I'd be unable to.

Since you have on the seductive demon form, that may be what's causing the tattoo not to change on your avatar.

Ah, I didn't even think of that. I forgot that the outfit I'm using has tattoos already added. I feel silly now. Lol Thank you!

You're welcome! And it's totally okay, I can't count the times I've tried to change the tattoo on my avatar while wearing an outfit that already has them, and wondering why I couldn't only to remember the outfit already has a tattoo. ^-^