In APA, use double quotation marks only to identify a quotation:
Yalom says, “we are, all of us, in this together.”
Use single quotation marks only to identify a quotation inside another quotation:
Frankl said, “to quote Nietzsche, ‘he who has a why to live for can bear almost any now.’”
Do not use quotation marks to emphasize a word. Use italics instead.
Commas and periods always go inside the quotation marks. Other punctuation goes inside the quotation marks only if they were part of the original quotation.