If you want some other kind of formatting, you can write a definition
of your own, analogous to \leftdisplays. You need only make sure
that \leftdisplaysetup
is called at the beginning of every display (presumably by invoking it
in TeX's \everydisplay parameter), and to define
\generaldisplay.
\leftdisplays expands the old value of \everydisplay
before calling \leftdisplaysetup, so that any changes you have made
to it won't be lost. That old token list as available as the value of
the token register \previouseverydisplay.