It’s been a VERY long time since I dealt with this - it was good few years ago and we were running on 2008/2012 hyper-V hosts at the time, so no idea if what I will post still holds BUT here it is nonetheless:
- In my experience what you’ve done is not even a permanent change. When I tested it in our syste, changing this is essentially reverted back automatically on reboot of the VM because the data is stored on Hyper-V host side and on each reboot it loads it back automatically. The change essentially needs to happen on Hyper-V host itself with the VM being shutdown and then when powered back on, it would load it back. The worst-thing about it though was that changing the VM configs on WMI side with the host running didn’t seem to work until you reboot the host itself (I guess the VM config is loaded up in memory; I think I tried to restart the vmms service but didn’t work and eventually ended up arranging full reboot of the hosts).
This said, the actual change I borrowed a powershell script written by this guy which is available in the following article: https://www.altaro.com/hyper-v/powershell-script-change-advanced-settings-hyper-v-virtual-machines/#Set-VMAdvancedSettings (I used an older version and had to even tweak it a bit cause it wasn’t working as given). You can reverse-engineer it if you want to check the exact WMI classes in which you need to make the change on the host. The guy does pretty good job to explaining it all in his article too. Good luck with it, it’s painful thing to say the least!