Selecting data points in Excel

I am new to Mac, and I am needing help selecting all of the data points in my Excel scatter point graph. When I try to select all the points on my graph by clicking one point first, it still leaves out four of my other points. This wouldn't be such a big deal if it didn't mess up my Equation and R squared value so much. I did some research already, but it never led me to whether this was a Excel or MacBook issue.