If and when I enter Taxable Spousal Support payments, the amount of the refund does not change. No taxes were paid on these payments so it is payable, is it not ??

Yes, Spousal Support payments are taxable to the recipient and deductible to the payor.

You should first check and see that you have entered your support payments as "deductible". To do so, click on Find (little magnifying glass), type in Alimony, highlight Alimony or Child Support Payments, click Go.

On the screen that appears, make sure you have entered the amount of your deductible support payments "twice", ensuring they are in the bottom box "deductible".

I received the support payments, not paid them out. I have entered them twice in the total received and total taxable boxes but the refund amount does not decrease

Your refund may not decrease depending on your total income and the Non Refundable Credits you have. Have a look at your Detailed Tax Summary and see if your credits exceed your tax payable. The addition of this income may not be affecting you depending on how much other taxable income you have.