Add or change animations and transitions

① On the left, click the slide you want to transition to.

② Click Slide  > Change transition.

③ When you add new animations, they are automatically set to "fade in.

④ Click the animation you want to change.

Change theme   

① On your computer, open a presentation in Google Slides.

② At the top, click Slide > Change theme

③ On the right, click the theme you want.