Does anyone have a multi purpose cooker thingy??

Does anyone have a multi purpose cooker thingy??

Well I have the crockpot Express one and I finally used the pressure cooker part. I made pot roast. The potatoes and carrots came out good! The roast was done butt tuff. I like when it just shreds and falls apart. How would I get it to that? I browned the meat then added everything and cooked for 40 minutes. Should I cook the meat for 45 minutes then add all the other ingredients after 40 minutes then cook for another 40 minutes??

Any tips?