I have 11 Honeywell TH8000 series stats. All purchased and installed at the same time, 1 year ago. Only one of them offers the "auto" option under "SYSTEM" How can I get the rest to offer me this option. I searched the Owner's Guide but can find nothing other than description.

You want auto changeover, right?

It's in the Install guide. Here:

http://www.ntsupply.com/files/products/69-1896EF.pdf

Try this

http://customer.honeywell.com/techlit/pdf/PackedLit/69-2693.pdf

Function 0300-1