Litter box training with an older cat

Had problems with my cat that I adopted from my nephew, she is 7 yrs old. She would pee on the carpeting and in the litter box at his house. When I got her, she started going for about 3 weeks in the litter box. Then started urinating on our carpeting a couple times a day. Went on YouTube , cat psychologist made comments that the litter box should be kept clean and away from the place that she eats. Well in my nephew's home and mine the litter box is not far from her food dish. Removed the litter box and placed it under a makeup vanity where she would have privacy. She now does her duty all the time in the litter box, thank GOD!