@HelenCooper @KatClifton - The recommended way to adjust the title that appears in the browser tab bar is to edit the information in the Publish options > Collection details panel. This title is shown when your item appears in web search results and when you share it on the web, such as on social media sites. This title can be different from the title that readers see on the collection home/overview page. (This capability is also available for stories and briefings.)
If you edit this information using ArcGIS Assistant or some other manual method, you may experience unexpected results, and the changes may be overwritten when you republish.
Owen Evans
Lead Product Engineer | StoryMaps