Rth7400d

I have a Trane XE1000 heat pump with an oil furnace as auxiliary. The problem is that I am not sure which setting I should use heat pumps * Multistage - heat pump with auxiliary heat pumps or * * Multi-stage heat - 2 stage heat and 1 stage cooling * . Can anyone help me?

use the heat pump heater ... it would run your heat pump first, then the warmth of your AUX gas for backup ... should also take note of changing your settings electrical heating to heat the gas in the installer set-up

After a review of the Honeywell web site I do not see RTH7400D listed.
What you have is probably not appropriate for a dual fuel system and cause damage to your system heat pump if it is used.
For dual fuel applications I prefer the Honeywell Vision Pro IAQ thermostat, but the 8000 Vision Pro can also be used. IAQ has a much broader scope.
None of these are available from the "Big Box" stores, but only heating and cooling professionals.