The store shows the legal name or the legal entity

On an individual Apple membership, the seller line is the legal name, not a brand and not a pen name. On an organization membership, it is the legal entity's name, not a trade name that exists only in chat.

What you accept before you ask

If you need a company name, ask for a company membership whose entity matches. Do not buy an individual membership and plan to rewrite it as any company. Apple's individual-to-organization path applies only when the membership holder is authorized to bind that entity. The renewal date is still a separate field.

Brand versus seller

A brand can appear in the app name. It does not replace the seller line. Guyi does not promise review or TestFlight.

Questions

Can the display name be a nickname?

No. Fill the legal name as it is. A sole proprietor usually stays individual.

Does transferring one app change this line?

The destination membership keeps the seller name already on that membership.

Ask for the account this guide describes

Send the spec to @hagee66