[whpalmer4]

There are two varieties of sorts you can apply. You can do a one-time sort, which rearranges the current data, but allows insertion of new data in arbitrary positions, or you can do a persistent sort which will keep rearranging the rows to match the order you have specified.

If you apply a persistent sort, you can use the values of multiple columns to do the sorting; the sorts are applied in column order from left to right. This allows you to sort your research notes first by author, then date of publication within each author's work, for example. The catch is that you may not realize this is happening, because each time you apply a keep sorted setting, it is added to the existing settings instead of acting like a toggle (in other words, choosing to sort by column B does not automatically clear the sorting by column C, it has to be explicitly removed). I suspect this has caused you some confusion.

Have a look at the help for "Sorting" in the built-in help in OmniOutliner. There are some points which I haven't covered here which will be of interest if you use sorting extensively.