I was forced to upgrade to GreaseMonkey 4.x with Firefox 56.0. My scripts stopped working. I wrote them, so I looked into fixing. I looked at the GreaseMonkey web site. I saw the general notice about the changes but could not find specifics. Didn't trust what I saw when I saw notes like "this script" hasn't been updated in years.

Fix up documentation. Provided example scripts with before and after changes.

Give warning if it doesn't work in Firefox 56. I tried Firefox 57, but that caused other problems for me.

Was able to turn off auto updated of GreasMonkey before downloading 3.17 version of GreaseMonkey. add ons > GreaseMonkey entry > more > click on off selector. See below for the link by Anonymous user e7bdbb to the download.

Robert
PS. There is snow on the ground as I write this :-(
PSS. FYI. Tampermonkey gave me a compile error on "for (var elmForm, i=0; elmForm=document.forms[i]; ++i)".