I’m Melissa, a Shopify Guru. Thanks for reaching out. If you would like to edit the description shown in the title tabs while browsing, this can be edited in your admin.
You will be able to edit this in the admin by going to Online Store > Preferences and will see the place to make the change here. This will allow you to change the title in title and meta description
If that section is currently blank, it defaults to using your store name. By adding a homepage title and/or changing your store name, this will change the name that appears in the tab title. The home page title will supersede your store name, so keep that in mind when editing.
Hope this information helps! You can reach out to the Guru team https://help.shopify.com/questions if you have any questions.
Have a great day!
Melissa | Shopify Guru
There is a chance your theme has something Hard coded if it did not work. There is code shopify uses to pull the info from the admin (known as Liquid). If your theme does not have it, was replaced, or the info was hard coded then it would not change when you change it in the admin.
You may also have cached info. You can clear your cache and try again
Information on clearing your cache based on operating system and browser can be found here: https://www.refreshyourcache.com/en/home/