It is the registry you have to change .....
Identify route locations
REG_DWORD: HKCU\Software\ESRI\Desktop10.1\ArcMap\DynSeg\IdentifyDecimalPlaces
Description: This controls the number of decimal places for numbers used on the Identify Route Locations dialog. Valid values are 0 to 10; anything else (or non-existent) will result in the default of 3 being used.
If you have the [ARCGISFOLDER]\Utilities\ArcmapAdvancedSetting.exe you can change it on the Linear Referencing Tab