My senior keeps having accidents all over the house, how do we manage this?

One thing that may help is to get her to the bathroom to (try to) use the toilet on a schedule, certainly after meals and snacks but as often as every couple of hours - while you won't eliminate the need for an incontinence product I used to think of every successful visit as one less depends to buy or one less clean up. If she is overflowing then make sure her pull up is the right size and fits snugly around the legs, you may need to try something with higher absorbency or a different brand although I don't think any are particularly good at handling feces. Put disposable pads where she sits. When my mom had very loose diarrhea I used snug fitting boxer briefs over her pull up to contain things on the way to the bathroom. And the little green machine by bissel was my go to for clean up.