(This bug entered on request of Mike Kaganski in comment 2 of bug 127252 - thanks Mike!) Ordering of the conditional formatting priority can be set in the “Conditional” menu → “Manage...” item → “Edit...” pop-up window with the "Up"- and "Down"-button (although this does not work properly; see bug 74074 - as proposed in comment 19 - and bug 127252). This is, however, not sufficient. When multiple conditional formats apply (even to different – but overlapping! - ranges), the order of priority of these should ALSO be changeable (with an “Up” and “Down” button in “Conditional” menu → “Manage...” pop-up window).
moving to new based on bug 127252 comment 2
Just wanted to point out that this bug is already covered by a previous one (with more comments and explanations): https://bugs.documentfoundation.org/show_bug.cgi?id=126047 *** This bug has been marked as a duplicate of bug 126047 ***