You are using a custom template so you would have to change the template to make a change to the functionality.
In one of the ShopSite templates, 3Column-Product.sst, in the [-- Define More_Info_Page --] section the code for the title that displays in the browser tab is laid out like this
- Code: Select all
<title>[-- IF PRODUCT.MoreInformationTitle --][-- PRODUCT.MoreInformationTitle --]</title>[-- ELSE --][-- PRODUCT.Name REMOVE_HTML --]</title>[-- END_IF --]
So it first checks to see if there is anything in the product field "More Info Title:" and if there is a value then it uses that, otherwise it uses the product name.
You would need to check your custom template and see if similar code is in it. The field "More Info Title" was added in version 8.1 so unless your template is way old, it could have used the tag [-- PRODUCT.MoreInformationTitle --] as the page title for the browser tab.
Also check that you have something in the Product field "More Info Title" or the Product name would still be used if the template has the same code as above.