Before a few months ago, I almost never explored using the different time ruler formats and never had more than one displayed at a time.  So, thanks for asking the questions and for the various comments. It now seems to make sense to me. As best as I can tell: (1) The + and - let you change the number of time-lines (1, 2, 3, or 4) and select specific formats you want to add or remove. (2) Right-clicking on the time line let's you choose which format(s) you want displayed.  However, thi