That was a question I got in 2 training sessions, and I had to admit that I didn’t really knew the answer. I was sure you could edit the time, but I didn’t encountered it yet throughout my sharepoint-browsing.
So I asked some of my collegues, and one (Tom Verhelst) came up with this one:
Via STSADM you can select:“stsadm -o setproperty”
You get a long list, and in that list somewhere you can edit the property “days-to-show-new-icon”
Somehow I am still hoping that one day there will be a STSADM with a GUI, so you dont have to mess around in code no more…