Order Number

[yy203173]

I am new in virtuemart, Recently I upgraded my virtuemart and Joomla by 1.1.3 & 1.0.12 to 2.0.6 & 2.5.6.

In the new site all order's order number is changed!

In the old site, The style of the order number is 00004082.
Now become to 7551_06ed3f6dc8d0b7c85e92acaa2d2.

I checked the MYSQL, the order number is get data from the colums "order number".

Anyone can tell me how to set up the new website allows to use the same order number style.

If feasible, the order number of the automatic increase, there need another set?

If this is not possible, how can retrieve the corresponding order with the original order number on a new site?

Sorry, my English is not very good, and the meaning of the expression may not complete! If anyone have any comments, I am very grateful!