When you're creating your own PowerPoint Template, you can format practically everything to make your presentation look exactly like how you want it to. To do this though, you will need to verse yourself with Master Slides.
Master Slides are there to help you build a template without using much time or effort. When you want a particular theme/color scheme/font style/image/background to appear in all your slides, Master Slides is where you want to add them to. Say, you want a particularly hued background or a brand logo in all your slides, add them to the master slide and all slides will automatically adopt these changes. Doing this will prevent any possible design inconsistencies and save you quite a lot of time from making changes to individual slides.
1. Navigate to the View tab and click on Slide Master in the Master Views section.
2. In the Slide Master window that opens up, the top-most slide on the left sidebar is the Master Slide. This slide is responsible for the basic design of all associated slide layouts.
3. As you select the Master Slide, you will see editing options on the top.
Say you want to add a background, simply right click on the slide background>Format Background or go to Background Styles>Format Background.
4. Further, you can format font. Just go to the Home tab, and make changes in the Font section.
Notice how all slides have been affected by the formatting changes.
5. Add images by going over to the Insert tab>Pictures.
After adding the image, you can format it in a number of ways as shown within PowerPoint itself.
6. When you're done with the master slide, you can format slide layouts too (learn how to use and edit slide layouts)
Get creative and play around with all the features available. Once you're satisfied, save the template you've created as a .potx file (how to save and use your PowerPoint template) and use it whenever you need to make an impressive PowerPoint Presentation.