Take a look at these resources and tips about citing in APA. If you have questions about how to cite something, contact your librarian. Keep in mind that the most recent edition of APA is the 7th. Be sure that any tools you're using to cite reflect that.
Things you MUST cite:
• Words or ideas presented in a magazine, book, newspaper, song, TV program, movie, Web page, computer program, letter, advertisement, or any other medium
• Information you gain through interviewing or conversing with another person, face to face, over the phone, or in writing
• When you copy the exact words or a unique phrase
• When you reprint any diagrams, illustrations, charts, pictures, or other visual materials
• When you reuse or repost any electronically-available media, including images, audio, video, or other media
Things you do not have to cite:
• Writing your own lived experiences, your own observations and insights, your own thoughts, and your own conclusions about a subject
• When you are writing up your own results obtained through lab or field experiments
• When you use your own artwork, digital photographs, video, audio, etc.
• When you are using "common knowledge," things like folklore, common sense observations, myths, urban legends, and historical events (but not historical documents)
• When you are using generally-accepted facts, e.g., pollution is bad for the environment, including facts that are accepted within particular discourse communities, e.g., in the field of composition studies, "writing is a process" is a generally-accepted fact.
source: Purdue Online Writing Lab (OWL)