Change the Copper Trace Length in Ultiboard

Select View >> Spreadsheet View. (By default, this will appear at the bottom of Ultiboard environment.) 

Navigate to the Nets tab in the Spreadsheet View. Look for the Net that you want to modify.  

Determine the minimum routing length from the origin of the net to the destination by routing manually a starter trace. Then, you can remove or delete this trace.  

Set the Topology of interest to Star for the traces you need to modify/match. This should change the Max Length and Min Length from N/A to a number. Change the Min and Max Lengths. The Min length has to be at least the value of your started trace from step 3.     
   

You can use the Autorouter Tool in the Autorouter Menu, to automatically create the traces and this will generate traces. Tip: Go to the Autorouter/place options and set the Routing mode to Gridless, this will give the router flexibility to go off-grid and match lengths.