Thank you. Easy enough after learing how to use Putty this morning. I manually edited the Transmission settings.json but some settings still get overwritten when the service is stopped and started, either from a toggle in the menu or rebooting the machine.
If anyobdy has an idea of a fix, I've noticed the following:
The "Download to:" always reverts to the "Transmission" folder.
"Use port forwarding from my router" is always unticked.
This is the case with both the 2.84 and 2.92 builds.