Welcome to the forum...
IÂ´d like to know if there is a way to change the order of the panoramas thumbnails.
There isn't - yet.
But Kolor has said they'll add such a feature at some point in the future:http://www.autopano.net/forum/t10048-panotour-1.5-b1-order-of-pano-list-and-thumbnails
I think they are always displayed in the order of importation of the panoramas in APT.
The thumbnails do seem to be displayed in that order.
But the order in which panos are listed in the drop down combo-box/list is determined by their Panorama names. By default the Panorama name (Panorama Properties/Name) is the filename.