The company I work for has a corporate identity I have to use for every presentation I create. I have created a master slide accordingly. However, my current work flow is to copy my old presentation, rename it, and change it to the new presentation. This, however, is highly inconvenient and I would like to globally import my master slide to be available for every new presentation I create as are the standard master slides.
I figured out, that I can File > Templates > Save as Template and it works for making a new presentation, but chosing the file as the master file for existing presentations just creates a white sheet.
How can I import my custom master slide to be available for all presentations I create/modify?