when loading Original 24bit projects in 64bit system it is changed to 16bit

I run win7 32bit and 64bit system and I use sonar x1
 
I didn't work at 64bit system much but lately 32bit system always get problem using plugin and playing project

so I have done several jobs on 64bit system

and now I notice in 64bit system all the 24 bit projects are automatically changed to 16bit

as I saved some projects wave files are also changed to 16bit

so I lost many 24bit files.....

this is so crazy

try to open file in 24bit option is enabled

does anybody know about this issue?

Just opening and re-saving a project won't change anything, and SONAR won't ever actually 'convert' a file in any case. Any destructive rendering always generates a new file with the old file remaining in place and the clip in the project referencing the new file.
 
If the bit depth shown in the Transport module is 16, that just indicates the any new recordings will be made at that depth per the setting in Preferences > Audio Data > Record Bit Depth as Thomas mentioned. Existing audio will not be affected; SONAR can handle having mixed bit depths in the same project.