Overwriting Categories Page Titles
Go to "Menu" then "Catalog" and then click on your "Categories" tab. For this example we'll edit the "Backpacks" category by clicking on "Backpacks" and then clicking on the "Open Page" Icon next to or above it.
Click on the "SEO" tab, then you will see the field "Page Title." Adding content to this field will overwrite the Default Title Tag value for this specific category.
When you click back into the store and click "Refresh" you will see that the Title is now "Backpacks."