Creating New Theme Colors

Hi y'all!

I have read a few articles on this topic, but would love a little more help. I have an existing Storyline project that I need to edit in order to reflect the company brand colors. Following what I have read, I imported a PPT file with the company brand deck into Storyline. Under the Design tab, I see a box with the desired colors [Aa], but when I click it, it not only changes all the colors in my existing slides, but also imports the design of the company deck, which I do not want. I just want to import the color palette so I can match the existing colors to that of the company brand. If I go to colors > Create New Theme Colors, it just shows customization options for text/background/accents in the original color palette. 

Does anyone know how I can import JUST the colors of the new PPT into Storyline but maintain the design of my current project? 

Thank you!