Q. How can I cite a Prezi, PowerPoint, or any slide presentation in APA 7th?

Slide Presentation with the author's name

The in-text citation in APA, generally, uses the author name and publication year wrapped in parentheses:

Slide 19 of the presentation stated that "7 in 10 undergraduates skipped buying one or more texts due to costs" (Allen, 2013).

and the reference would be:

Allen, N. (2013). OER and solving the textbook cost crisis [PowerPoint slides]. Slideshare. https://www.slideshare.net/txtbks/textbooks-28013186

Slide Presentation without the author's name

If the following example did not have an author's name attached to it then the in-text citation would use the title of the presentation instead:

Slide 19 of the presentation stated that "7 in 10 undergraduates skipped buying one or more texts due to costs" (OER and solving the textbook cost crisis, 2013).

and the reference would be:

OER and solving the textbook cost crisis. (2013). [PowerPoint slides]. Slideshare. https://www.slideshare.net/txtbks/textbooks-28013186