Hi Dennis, 

the purple box: I suppose you mean the purple background in the title https://prnt.sc/e5nKFMQCpEc9 ? This is the background of the title area, you can learn more about it in the following documentation articles: 

https://docs.codex-themes.com/article/336-title-area

https://docs.codex-themes.com/article/439-title-area

This title area (and all its settings) can be controlled globally for the whole website via Theme Options (https://docs.codex-themes.com/article/336-title-area) or per product category (as you have requested) here https://docs.codex-themes.com/article/522-product-archives or individually  per product here https://docs.codex-themes.com/article/439-title-area 

You can also build your own custom title area using TheGem templates builder https://docs.codex-themes.com/article/206-general