How to install a skin in Minecraft [TLauncher]?

I recently tried to install a new skin in Minecraft through TLauncher, but encountered problems. I followed all the instructions I found, but the skin does not appear in the game. It’s terribly annoying because I spent so long choosing and customizing it. I’m starting to get confused with the settings and don’t understand what I’m doing wrong. It seems like I’m missing something, and it’s causing real anxiety. Maybe someone has already faced something similar and can explain what’s going on?