I'm a bit confused my guy.
Answer:
To make changes to the format of all your slides at once, using the Slide Master is probably the best idea. The Master is what controls how your slides will look: what fonts, colors, bullets, etc. that will be used on each slide.
Explanation:
Select the View tab, then click the Slide Master command. The presentation will switch to Slide Master view, and the Slide Master tab will be selected on the Ribbon.
