Karina R. answered 12/05/19
ESL/English/Spanish Specialist (M.A.)
If you are writing an academic paper, speaking with a boss, or taking an English exam, you want to use "All I know." That is standard, academic English. "Alls I know" could be considered informal and impolite in certain situations. Some people might say, "alls I know" in everyday life, but they would need to write "all I know" for an academic assignment.
Best of luck! Keep writing!