I appreciate the excellent tip! Mine was set to Default. I changed it to Load Last, then changed all 4 probes to 10x, then restarted, and now I see it saves the 10x setting. Great! Thank you!
The first version of firmware for the DHO800/900 I couldn't even figure out how to change the probe attenuation!
It's this is still not a great solution IMHO because you usually don't want the probe config changing on a "default" button press either, which is a very common use case.
On a scope with no readback, or supplied without readback probes, going to "default" (either from boot or by pressing the button) should either not touch the probe config or set it to 10X. ISTR the same applies to Rigol's MSO5000. The solution in that case was that I have my own default setup config, including probe settings, and I use this rather than the scope's default button. (Other things I like is to have as my "default" are the trigger point at 10%, expand around trigger, and a Ch1 rising edge trigger at 1.5V).
As a comparison, the DS1000Z are at 10X after a default button press.
Even the Tek TDS 2024B I have here defaults to 10X (I can't remember the last time I turned it on, it was many years ago, but the clock is only 6.5 minutes out: the plastic's starting to get brittle though).
The Siglent SDS1000X-E & SDS2000X+ have a better way of implementing this with the Default button using a user-defined default, although even after a factory reset the channels are at 10X.
I am wondering if it's in response to "customer feedback", with noobs getting confused: I could certainly see that happening.