touchpad on I15-7547-4020SLV is overly sensitive

I purchased this brand new Dell laptop at Best Buy because it seemed to perfectly meet my needs.  I've been trying it out now for 2 days and it's been a terrible experience for ONE REASON ONLY: The touchpad behaves so erratically that I cannot use it.  I get my cursor positioned to then TAP (such as to drag the end of a screen to resize, or to enable or disable a check mark in an online website box) and as I lift my finger the cursor moves just enough to require I try again and again.  This seems to be a function of the humidity in the air.  I think if there were a sensitivity adjustment on the touchpad it would solve the problem, but no one seems to know how to get that done.  If I can't fix this, I'm going to be forced to return this machine to Best Buy.  Fortunately, they have a nice return policy.  But I really would prefer to keep the machine if I can fix this. That means I need prompt help so I don't over-run my return trial period.

Also, there's some kind of error on the DELL Chat process.   It scans my Service Tag, produces the same result as I can read on the bottom of the laptop, but the chat window won't open because it INSISTS my Service Tag doesn't belong to this computer!  So, so far my experience with Dell hasn't been encouraging.  Can you help change that?