As a brand owner or authorized distributor, can I control the content of my listings on Amazon that were setup by resellers?

By default no seller owns a listing, Amazon owns all the listings. The seller that set up the listing initially has a certain level of control since they created it. But any reseller on a listing is able to suggest changes to the listing at any time. Such as updating images or changing content. These suggestions are not guaranteed to be accepted by Amazon. A brand owner (with brand registry) will get priority in suggested changes over a reseller. There is a lot of discussion and ambiguity about this, see this reddit post

The first step for a brand owner is to enroll in Amazon’s brand registry. In order to do this the brand owner must have a registered trademark from a local government agency As part of the enrolment process the trademark must also appear on the products or packaging. More details on this can be found here. Also check out A guide to brand registry

As a worst case scenario, a brand owner is able to open a new competing listing.

For official distributors: The brand owner, through brand registry is able to connect resellers to their brand registry. (see screenshot below). This connection gives you access to some brand benefits like A+ content. It’s not 100% clear as to whether this lets you have the same control over the listing as the brand owner, but we suspect that this is the case.