Clarify.
Sounds like you have it bound to your account (since you've been using it), now you sold it and the new owner is saying it's bound to another account.
I.e. you have to go into the DJI Fly app and remove the drone from your account so the new owner can use it.
Sounds like you're looking at asking prices and not "sold for" prices, common mistake on ebay.
There are always people asking for unreasonably high prices, and that'll simply never sell until they adjust to the market.
There are no "one size fits all", if that's what you want then best stick with the defaults and get used to them.
Otherwise it'll depend on your own feelings and what you're trying to do, so experiment.
How did you buy a P4P+ new last month and at that price? It's a 9 year old model and there would be WAY better choices for $1.2k...
Maybe you can scour ebay and find a complete used one as replacement, shouldn't be worth more than $200 or so these days.
The point of log is to capture more dynamic range, and to do that the sensor must be working in a certain optimal range. Bringing it down to 100 would wipe much of the benefit.
Some big cameras actually require 800 or even 3000 for max D/R in log...
What it offers is the opposite of a few clicks, it's more flexibility than standard... but at the cost of knowing what you want to achieve and how to do so. Gotta learn and spend the time.
Eh, again a thing that was designed as a PR stunt but was never gonna be made because it wouldn't ever be practical/viable...
You could submit your interest and there probably was nowhere near enough. Their other similar gadgets from the same time that actually shipped like the Astro failed...