Don't want to confuse things as I don't know how similar F6 recording 32bit float is to F8 recording 24bit, but I deal with a similar situation with regards to monitor/mix levels on F8. I generally keep input trims set the same recording to recording, and as a general starting point, I would like to have the monitor/mix levels remain set the same each time as well ..and they are unless the channel input knobs are accidentally adjusted. The problem is they are easily knocked, throwing off the monitor/mix for that and each subsequent recording until being readjusted again. Fortunately this is mostly an annoyance, in that it is not effecting recorded levels. Still its nice to avoid.
The best fix I've found is to set the lock-function to lock only the channel knobs (I also lock-out the slate-mic/test-tone switch) but none of the transport controls, menu button nor input knob. I would leave them locked out all the time if I could, however, since the lock-function resets to unlocked upon power down, each time I power up I still need to manually check all the monitor/mix track knob positions prior to locking them down, but they then will remain unchanged during the recording session, and the monitor/mix levels stored with the files will reflect that desired generic starting point.