Audio bit depth / sample frequency change - help!

Hi Having updated my hardware recently I've changed the default project settings for Sonar to 24bit / 48kHz for audio recording. I have a number of older projects in 16bit / 44.1kHz and loading them into Sonar now results in warning messages about my audio interface (UA-1G, now set at 48kHz for recording) not matching the older audio settings. I can understand this. However, my question is this: is there a standard way of dealing with audio properties conflicts like this? Do I convert the old audio to the new settings? Do I stick with the old settings with my old projects? Does Sonar have a built-in way around this that I haven't found? Any help greatly appreciated. Thanks SJD X2a

Seems the simplest solution for me has been to go to the ASIO panel and change my interface back to 44.1. In the end I had so many weird things happen I have ended up sticking to 44.1 for now until all old stuff is finished ,,,, I'm close. 

Gustabo posted same time as me and now  reading his seem worth a try

This is not a sonar issue,  but a sound card issue. I can load and play projects in 16 bit, 24bit, 44.1kHz, 48kHz, 88kHz, 96kHz and 192khz and i get no warnings. My sound card drivers change to the project at hand.

Your issue is caused by your sound card not having drivers written to change sample rates at will. most sound cards made for recording can do this. Obviously, your cannot.