How to Change Your Amazon Marketplace in AccelerList

Step-by-step

Log in to AccelerList
Go to Settings (left sidebar).
Click the Connection tab.
Under Amazon, confirm you’re on the Amazon sub-tab (you’ll see your Seller ID / Primary Marketplace).
Click Re-Authorize Amazon (button on the right).
(This opens the “Authorize Amazon SP-API” pop-up — like in your screenshot.)
In the pop-up, open Select Marketplace (dropdown).
Choose the marketplace you want (ex: ATVPDKIKX0DER for Amazon.com / US).
(You may also see other options like CA or UK, depending on your Amazon account.)
Click Continue to Amazon.
You’ll be redirected to Amazon Seller Central.
Review the authorization page and click Accept / Confirm (approve the connection + terms).
After approval, you’ll be redirected back to AccelerList.
Back in Settings → Connection → Amazon, confirm the Primary Marketplace now shows the marketplace you selected.

If you don’t see the marketplace you need in the dropdown, it usually means that marketplace isn’t enabled/available on your Amazon seller account.
If the page doesn’t update after reauthorizing, refresh the browser (or try an incognito window).