Editing the master slides in a discussion allows you to essentially set a default font style, font size, and font style color for your discussion slides. Furthermore, you can select background color( s) plan and include icons that you desire to have placed every time you add a new slide to your presentation..
How to edit the master slides and re-use them in your Google Slides discussions is shown in this brief video..

Two times in the last week Ive gotten concerns from readers about Google Slides. In both cases the concerns were related to using fonts and color design without having to manually alter them for every single brand-new slide included to a presentation. The service in both cases was to alter the master slides in the discussion..