How to change the Zendesk account name on the login popup window in Help Center.
You will need to go to Admin > Settings > Account > Branding > Your Zendesk account name and update it. The change will reflect on the popup window in Help Center.
If your account has multibrand, you need to go to Admin > Manage > Brands and select the brand for which you want to change the name. You can set a new value in the Brand name field and save the changes on that brand which will update the name on the popup modal in the Help Center.
If you want to change the name that appears on the tab or other places in the Help Center, you need to do that in Guide. For more details, please see the article Updating the name of your Help Center.