tsunanaaAdminAlmost always one cause: **your forum account is not linked to a Minecraft
account yet.**
The fix
Go to account settings and use Link now.
That looks your Minecraft name up and stores the account's unique id, which is
what the skin renderer actually needs.
Until that is done, the site only has a name — and if that name does not
belong to a real Minecraft account, the renderer has nothing to draw and falls
back to the default character.
Why the name alone is not enough
Minecraft names can be changed and reused. The unique id cannot. Storing the
id is what makes your skin keep working after you rename, and what stops your
profile from picking up somebody else's skin later.
If linking fails
"That name does not exist" — check the spelling, including capitalisation
patterns you might have got wrong. If it still fails, the account may have
been renamed.
"Could not check right now" — Mojang's lookup was unreachable. This is
temporary. The link is simply not saved, nothing is broken, try again later.
You changed your Minecraft name
Use Link now again. It re-checks and updates.
Your skin changed but the site still shows the old one
Skin images are cached, by us and by your browser. Give it a while, then force
a reload of the profile page. If it is still wrong after a day, that is worth
reporting.
One thing linking does not do
It does not prove the account is yours. The lookup only proves the account
exists. That is why linking a name gives you a skin and a display badge and
nothing else — no ranks, no permissions, no ownership claims. A real ownership
check would need a code entered in game, and that does not exist yet.
Which also means: if somebody links your Minecraft name to their forum
account, they have gained a picture and nothing more. Still worth telling us
about, but nothing of yours is at risk.