What is the best way to import Content Library 360 Slides so they match your overall theme?

MichaelEtzel​: If you reformat objects on the slide, that tells the program that you want to break from what's on the Slide Master. That means reformatting the Slide Master won't change those objects. 

If you haven't reformatted objects on the slide, updating the placeholders in the Slide Master should also reformat the associated placeholders. 

Imported Slide Masters also have their own Colors and Fonts, and those impact all objects on the slide. So those should be updated to match your branding.

Here's another "Four Column" example, this one from the Vitality theme. Here's the original imported slide: 

This is what the slide looked like after I switched the Slide Master's Colors and Fonts: 

It can definitely get crazy if you have multiple Slide Masters, so here's something else you could try:

• Select and copy every placeholder on the imported Slide Master (e.g., items on the Four Column Vitality layout). 
• Go to your Slide Master, and insert a new layout.
• Paste the placeholders, and reformat them as needed.
• After you've copied all the imported layouts you want into your own Slide Master, delete the imported Slide Master.

Or perhaps just recreate the layout you like from scratch in your Slide Master. 😊