Hello.

I think when you click on the Brand field on the Vital info, you should get a dropdown box with how you registered your brand, in that selection. Click that. (If you’re not brand registered, you wouldn’t see a dropdown list - but in both cases you could still manually type something in)

The key identifier is something like manufacturer part number, that helps distinguish your product/listing. If you select your brand from that dropdown list, the listing page will then usually ask for you to put something into say, the manufacturer’s part number field. It will expect a value here, if you have MPN as your key identifier, once you’ve selected your brand from that first dropdown list.

Make sense?

Be aware that if you had the manufacturer’s part number field filled with data already BEFORE you brand registered, it can “lock” those values in at the time of registering. This is something that is not mentioned very clearly prior to registering, and if you’re selling this ASIN/SKU across multiple marketplaces (Like EU), it can cause massive issues if you have one country’s listing that has a different key identifier (manufacturer part number for example) compared to another country’s value for that field.

There should be a warning that says, before you brand register, either input and align all the key identifier fields (that you plan to use) so they’re the same, OR… just delete them so it’s blank. If it’s blank, it means you can do what you want later (after you’ve registered). Though typically, if it is blank, once you input the brand name in the Vital info, it will outline the blank field in red, because the page will expect you to put something here before you can save the edit.