Changing Title of Page (metadata)

I've been having a rough time with this for the past two years, I keep coming back to it... it's hurting my seo... I need to be able to change the title of the page for the "product tag pages" where in the code can I do that?

here's the page for example - it's naming it after the first product shown. so this is the title of the page -Heartfelt Warmer | Buy Scentsy Products

I don't want that.. I want the page title to be called the actual name of the product tag, wich is "Candle Warmers Large"

Here's the link:

Please help!