Q. How do I cite information in my paper if it come from material cited on a PowerPoint slide? I'm using APA.

This would be called a Secondary Source

The preferred thing to do is to actually find that quoted source and cite that one directly. However, if that's not possible refer to the primary source and refer to the secondary source by using "as cited in".

For example, if you read a paper by Knecht in which they were citing Gilbert you would use the following in-text citation: (Gilbert, 1985, as cited in Knecht, 2020).

In your reference list you would only use the reference for the primary author, in our example that would be Knecht.

APA 7th manual section 8.6 Primary and Secondary Sources