I believe trying to download from the Apple Store will detect what OS you currently are using on your computer and, by design, will not give you the option to download an earlier version from them.
I also suspect, that even if you find an older version to download, you will have to do so on a separate drive (8 GB flash drive, for example) AND erase the current drive that contains the later version before installing the earlier version on it. (Perhaps you already realize this.)
P.S. Tried to send you a PM, Bob00001, but your preferences appear to be set not to accept PMs from other members.
