Corel version 12 and 21

I have corel version 12 on an old computer that I have had since about 2006. II use for my drawings for my laser. It is a laptop.

I had to replace my desktop and it won't run version 12.  It won't open large files.

My problem is I can't save filles from corel 21 in version12 (only back to 15).  I am finding 21 so different and difficult compared to 12.

Any suggestions?  Does corel sell older versions that save in version 12--Newer than 12 but older than 21.

Any help is appreciated.

I have had a suggestion of using CMX legacy format.

Corel tells me 12 is old and they don't support it any more--and basically tough.

Susan Karatjas