I recently restarted learning math. My circumstance is I forgot most of math and I am self-studying computer science.

I have been using these:

KhanAcademy

https://www.mathsisfun.com/

and to a lesser extent:

https://learnaifromscratch.github.io/math.html

I saw in a reply you are currently spread thin, but I hope you get a chance to restart.