Won't stay in 1st gear

[boneshakin]

We received our two RadRover 6+ a couple of weeks ago.  I have noticed that my bike (step over) will not stay in first gear.  When I shift into 1st and take my thumb off the shifter it immediately goes back into second gear and attempts to switch to third as well but does not quite make it.  The bike has only 40 miles on it.  I am assuming Rad did a poor job of setting it up before shipping it out?  How would I adjust this?

Thanks