This looks like a very common question, but I haven't found a good enough solution on this forum. It's Filemaker 20 that is out now, and does it still not have a convenient way of enabling/disabling field editing on the layout? I mean dynamically depending on desired events, of course. I need to lock the entire record from editing when its status changes to "Closed". Am I supposed to add another layer to all fields and make them hide and show? Please don't say that 🫠 

you can use FileMakers built in privilege sets for the table in question. Disable editing if the record is closed. 

How do I use them? Is there script steps for this?

This goes to the heart of FileMaker, you setup a user privilege set and edit the options to restrict access for the user currently logged in. 

There are many conversations here about FileMaker security and how to properly configure permissions for your users. 

Only relying on scripting is not security and users can thwart any obfuscation in order to gain access.