DT 3.91 Editing PDF documents not working anymore

Please watch my words, I am not reluctant to using the feature, but I am averse to spending time studying the case to understand the implications and furthermore, to figuring out how I change a hidden preference.

BTW, cgrunenberg himself called it a hidden setting.

Did I understand the following correctly?

  1. Apple has once again been playing with the PDF kit.
  2. Enabling ForceEditablePDFs will make most files editable, but I have to expect that the risk of damaging PDF files will increase.

In case, I want to use the preference ForceEditablePDFs, how do I turn it on?
TIA