Hi Francis.
Audio files are now saved by default to an audio folder nested inside the folder location that you save the project. Copying the parent folder that contains both the audio folder and the project to the new computer is the easiest way to transfer.
An alternative is to save the file as a ' cakewalk bundle'. It will contain a compressed version of all audio files that will be extracted by Sonar when it is opened on the new computer, then save it as a regular project.
Either way, bear in mind that an identical version of any vst plugins used in the project need to be installed on the new computer in order for it to load correctly.