I use EchoVideo to share slides. Each slide has the option to hide a slide from student view by clicking on "hidden slide" when you hover on the top of the slide. I reveal each slide one by one, thereby allowing students to go back to previous slides without skipping forward to slides that have not been reviewed.

Problem: Once all the slides have been unhidden, I need to go back and manually hide each slide one by one the next time I present the slides.

Solution: Create a one-button option to hide all the slides at once.