I have several presets saved for different applications, such as:
 

• Exporting for Mastering
• Exporting for CD Burn
• Stem exports

There's a couple more but their purpose escapes me momentarily 

The OP's pic you cant really tell if its the bounce to tracks menu or the export menu (cant see the header) they both look almost identical.
Bounce to tracks default is 32 bit (and with good reason due to floating point within Sonar).
But my default export bit depth has always been 16. I use presets as well but I can ever remember seeing the Export options bit depth at 32. It must have recently changed because mine is now at 32 as well. that's recent.

SONAR will remember your settings from the last export, so once you've exported at 24 bits, that will be the subsequent default.
 
I just wish it was able to remember separate defaults for each export format. I normally export WAV files to 32 bits but FLAC files at 24 bits because the FLAC encoder can have problems with floating-point data. No big deal, though; I've just gotten into the habit of having a quick look before I leap.
 
 

bitflipper
SONAR will remember your settings from the last export, so once you've exported at 24 bits, that will be the subsequent default.
 
I just wish it was able to remember separate defaults for each export format. I normally export WAV files to 32 bits but FLAC files at 24 bits because the FLAC encoder can have problems with floating-point data. No big deal, though; I've just gotten into the habit of having a quick look before I leap.
 
 

You are correct. it will remember. however this past update must have reset something because I never export at 32 and mine is set for 32 right now. im still trying to figure this one out.

if i select the preset [what you hear,] it change from 32bit to 16bit...(sonar 5)

bitflipper
SONAR will remember your settings from the last export, so once you've exported at 24 bits, that will be the subsequent default.

 
Sometimes it reverts back to the default settings. It used to revert every session but now it only does it sometimes. Anyway I use saved presets so it's not a problem.