Remove the product from your TikTok Showcase and add it back: re-adding applies the current commission rate, so the product picks up the higher rate straight away. This is also how you remove a Soco link from one product; you never need to unlink your whole TikTok account to change one link.
When you'd need this
A brand set you up with an invite-only or custom rate, arranged directly with them. Soco has no visibility into private agreements like that: it only sees the standard commission links on TikTok Shop, so it can't tell your existing link already pays more, and Add All to Showcase can replace that higher brand link with a standard one. Products with special deals are worth leaving out of Add All in the first place: Will Add All replace a higher rate I get directly from a brand?
Switch the link back
The fix happens inside TikTok, in two moves plus a check:
Open your Showcase, then swipe the product to Remove, or tap the "..." menu on it and remove it.
In TikTok, go to TikTok Shop, then Manage Showcase, then Add Products. Search for the same product and add it back.
Check the rate on the re-added product: re-adding applies the current commission rate, so if the higher rate is live, it comes back at the higher rate.
If a brand sent you a targeted invite for the higher rate, add the product from that invite instead. If the product comes back still showing the lower rate, the higher rate isn't live on the offer yet; that part is set by the brand, so check with them that they've applied it to your account.
Videos you already posted
Switching the link updates your Showcase and new content going forward. Posted videos keep the rate that was active when you posted them: TikTok only lets you relink a product on an existing video if that product becomes unavailable, so past videos stay on their original rate.
Next steps
The related money questions: