I have Garritan Aria Player installed on my system (64-bit Windows 7) and am trying to use it for output for playing the MIDI tracks in Sonar Artist. I managed to succeed in getting the Aria Player 1 softsynth inserted, was able to assign it as the output for each of the MIDI tracks (replacing Microsoft GS Wavetable Synth), and configure the instruments I wanted for each track in the Aria Player interface. Playing the tracks used the Aria Player instruments as expected. I saved the project. When I came back, the Aria Player 1 Primary Output: Stereo track created by inserting the softsynth was still there, but I had to reinsert the Aria Player 1 softsynth again with the browser and reset all the MIDI tracks again to use Aria Player 1 instead of Microsft Wavetable .  Question: is there a way of saving this configuration with the project, so I don't have to redo everything every time I close and reopen the project?  Thanks. 

Did you save it as a CWP file or as a MIDI file? Simply saving it if it was started from a MIDI file it will default to a MIDI file when you save unless you change the file type to cwp. You need to use save as. 

As above.
Would be helpful to state Sonar version.
May not be applicable to you, but the rule is always switch on your controller before you start Sonar.
Also if you want to speed up your workflow check out Sonar project templates, and Sonar track templates. Ta.

DOH!  Thanks, guys. Yes, I had opened a MIDI file. Although it eluded me while I struggled with this for hours, it finally occurred to me that saving the MIDI file wasn't going to preserve anything except MIDI. Saved it as a project file and voila! So just signed in to answer or delete this myself, but you guys beat me to it! You guys are amazingly helpful!  Thanks again.

Welcome to the forum Richard. I'm glad you figured it out. If you need us we are here.