I’m having difficulty in specifying whole/half tone trills. I’m not finding the feature that the manual says should be available. When an accidental does appear over the Tr symbol, I can double-click that and amend the text. Apparently m2m makes a half-tone, M2M a whole-tone. However, I can’t double-click the space where no accidental currently appears and type one in, or at least not as far as I can see.
IIRC You set this in the Properties panel for the trill. In the Popover, “tr m2” gives a minor second (with flat added) and “tr M2” gives a major-second trill.
(But that only seems to work once I have entered the trill and double-click on it.) 
That seems to have worked – thanks.