My powder foundation stopped working for me? help?

i've been using Mark's powder buff in buff, i think that is what it is called correct me if i am wrong. it worked best on me because it matched my skin color and it covered some acne scars and ended up giving my skin this nice even glow. however, lately it haven't been working for me because each time i apply it now my skin looks dull and it just seems powdery unlike before it blended in with my skin, it also stopped covering my acne scars. i was told that after a while you have to change things up and try a different product. does that mean i have to start using liquid foundation or i just have to try a new powder foundation? i have tried bare minerals and i did not like it, i've tried cover girl, Maybeiline, Loreal,and a bunch others. i always put on concealer before applying my powder foundation but lately my acne scars are not getting covered. do you guys recommend a certain product or advice? i really don't like liquid because it feels packed on, i mostly like to wear make up that doesn't feel heavy or greasy when wearing it. thanks in advance i know it is a lot to read.