I just loaded some old projects with no audio track and only instrument tracks. What I realized is the sample rate keeps changing based on the sample rate selected in Preferences>Driver Settings>Default Settings for new projects. i.e if I change my sample rate to 48000 and open a old project, the project opens in 48000. If I close the project and change sample rate in preferences to 44100 and open the same project, it now opens in 44100. Isn't this setting only meant to apply for new projects?? BTW if the old project has a audio file in it then Sonar seems to remember the sample rate I kept while creating the project. Is this a bug or is it meant to be like this? Doesn't the VST and VSTi sound little different when kept at different sample rates? Then why dont sonar remember the kept sample rate?

Makes sense that it would work this way. The sample rate isn't locked to anything but a wave file. If it doesn't detect one then a default is assigned based on the preferences. VSTi are real time processes until you freeze them and create a wave file.

Yeah, I like it like that! 

Right, project files are agnostic about the sample rate until you add an audio file to it. At that time the sample rate is set to the "default for new projects" as set in the audio options. If the audio file is at a different rate it will be converted to the target rate. Once this happens the project is now locked to that sample rate.
 
One reason projects don't have a fixed sample rate is because in projects with only virtual instruments and plugins, you can change the sample rate and they will adapt to the new rate.

Noel Borthwick [Cakewalk]
Right, project files are agnostic about the sample rate until you add an audio file to it. At that time the sample rate is set to the "default for new projects" as set in the audio options. If the audio file is at a different rate it will be converted to the target rate. Once this happens the project is now locked to that sample rate.
 
One reason projects don't have a fixed sample rate is because in projects with only virtual instruments and plugins, you can change the sample rate and they will adapt to the new rate.

Word from the top! 

Noel Borthwick [Cakewalk]
Right, project files are agnostic about the sample rate until you add an audio file to it. At that time the sample rate is set to the "default for new projects" as set in the audio options. If the audio file is at a different rate it will be converted to the target rate. Once this happens the project is now locked to that sample rate.
 
One reason projects don't have a fixed sample rate is because in projects with only virtual instruments and plugins, you can change the sample rate and they will adapt to the new rate.

Please get back to work Noel. You don’t have time to be here answering questions. We can do that. So hurry up and get back to working on the release of the new version of TDFKA-SONAR. 😉 Honestly though it’s great to see you here.

There used to be a pop up dialog window at the beginning of every "New project" for: sample rate and bit rate.
That is no longer there. I kind of liked that myself.

The new project dialog still has drop downs for sample rate and bit depth but these values have never been written into the project. They are temporary overrides of the default values for the new project. If the project is closed without recording audio, the sample rate will revert to the default settings for new projects in preferences. Whether a project has recorded audio or not, the record bit depth for future sessions is read from preferences.

scook
The new project dialog still has drop downs for sample rate and bit depth but these values have never been written into the project. They are temporary overrides of the default values for the new project. If the project is closed without recording audio, the sample rate will revert to the default settings for new projects in preferences. Whether a project has recorded audio or not, the record bit depth for future sessions is read from preferences.

Great info Steven. Thanks.
I work from project templates that I update often (have been for years).
Don't have this issue myself because the templates along with preferences are set up the way I like it 24 bit 44.1.
But my templates used to prompt me with the New project dialog box. But that changed 6 months ago or so.
When people were complaining they needed to name their projects upon start. So Cakewalk changed it.

Thanks for the very helpful replies. That makes sense. However, I wish sonar could also remember the sample rate and bit depth kept for projects even in midi only cases(A checklist in preferences to have this option enabled or disabled will be ideal). I opened a few old projects and they kind of sounded different. This is because of the new changed sample rate. I kind of liked the way the track sounded with old settings. Just changing it again to 44100 gave me back my old mix exactly the way I left it. Hope there is an option for this.