Dell Laptop Touch pad issue

The computer is a Dell Laptop Inspiron 15 3000 series. Of late, the touch pad (ie. mouse) has been acting up. To describe the issue when you put your finger on the touch pad and move it around, the mouse pointer reacts as normal. But when you go the the "Scroll down vertical bar" on the right hand side of the screen, take your left hand pointer finger and press on the lower left corner of the touch pad, HOLD IT DOWN and then take your right hand (pointer finger) and try to move the scroll down bar "DOWN" nothing happens. Sometimes I "lick" my pointer finger and it makes the scroll down bar move. Other times when I go to scroll "Down" i.e. pulling the bar down, nothing happens. BUT, when I move the scroll down bar in an upward motion (on the touch pad) the scroll down bar will move down. Additionally, the "Cut and Paste" feature when you want to "Highlight" a word or phrase, copy it and then past it somewhere else, this feature is TOTALLY GONE. NO-FUCTIONAL. I've been to "Settings" "touchpad" and adjusted the sensitivity but that hasn't helped the issue. Can I just have the computer have a new touch pad installed? OR, what are your thoughts?
All comments are appreciated in advance.