If as I am adding additional W-2 forms for the multiple jobs I have, my return is becoming less and less. I don't understand how that is correct?

Your tax return will be based upon the total amounts of income and withholding from all of the W-2 forms that you receive.  Don't worry about the refund amounts at the top of the screen until you have completed your return.

Do you mean your refund is less and less?  It is hard to say because we can't see your return.

You may not have had enough Federal Income Tax withheld from these other jobs.  As you enter more income your taxable income increases, and so does the amount of tax you owe.  If you did not have enough withheld to cover the additional income, it will decrease your refund.