Please add spaces between words: IfyourPCopensthe.REASONfile,butit'sthewrongapplication,you'llneedtochangeyourWindowsregistryfileassociationsettings.Inotherwords,Windowsisassociating.REASONfileextensionswiththewrongsoftwareprogram.
If your PC opens the .REASON file, but it's the wrong application, you'll need to change your Windows registry file association settings. In other words, Windows is associating .REASON file extensions with the wrong software program.