When is double space used in APA?

In my opinion, the APA Manual is contradictory (certainly not specific enough) on this topic. My answer to your question would be footnotes (and in instances tables and graphs because it may not make sense to double space and may be confusing). A direct quote from the related link (which is quoted from the APA Manual) is: "Double-spacing is required throughout most of the manuscript. When single-spacing would improve readability, however, it is usually encouraged. Single-spacing can be used for table titles and headings, figure captions, references (but double-spacing is required between references), footnotes, and long quotations [this is sometimes referred to as block spacing]" (APA, 2001, p. 326).