I would like to know how can I quickly ease the slightly swollen parts in this picture, I tried 120 grits sand paper and it didn’t work. also I can’t ...

Thank you so much for the information. Also, the featured filler is comple  dried out can I restore it for use?

Thanks for your advice! I’ve actually covered it with primer coat. Does it matter to level it with the wall. Does it matter once I gently sand it off? ...

     I wonder do I still have to apply one more layer onto the putty or I can simply sand it and paint on it.