Hmmm, this resolves my issue and provides me with a workaround. I can now use the chips calculator tab to assist me with starting stacks in cash games where we use fractionals but because the toggle is associated with the chip count token on the layout I just have to remember to change the setting when we use the clock during a tournament.
I don't normally use the software for a cash game so this isn't really a big issue for me, though it occurs to me that I may end up creating a new layout for a simple "countdown-to-get-the-degenerates-out-of-my-basement" timer