I ticked all the boxes saying "don't save parts" and "don't ask me again" and it keeps asking me with those boxes ticked every single time.
Here's a macro I use to save assemblies. It only saves files with write access and ignores most others. (Sometimes a warning or two gets through.) I keep it on my macro toolbar.
Does not give warning if used on a new file that hasn't been saved yet!
Retrieving data ...