Multiple choice test number 17

Hi,dear Mr.Daerr!
I’ve just taken the multiple choice test number 17. I got right at 9 of all 10 questions at first attempt. As usual I repeat the test,I saw my mistake and I got right at all questions. When I had to choose between “for” and “about” I was confused. I don’t know when to use “for” or “about”. Then I saw that “about” is appropriate. Could you explain me when to use “for” and “about”?
Many thanks for everything!
I look forward to your next lesson.

Have a good night!
Best regards,Peter.