5 year old Beagle potty training. ?

I adopted a 5 year old beagle from the animal shelter. Her name is Brinks. Since I've gotten her she urinates/ poop on the carpet. I take her outside so she can go, but she never goes outside, no matter how long I let her stay out. As soon as we get back in she uses the bathroom in the house and I immediately take her back outside. I also leave a dog training pad on the floor and she will sit next to it and urinate/ poop on the floor. Anybody has any ideas on other ways I can go about potty training her?