I prefer to work in one large
org-agenda file. I have my appointments and notes in there from the past five years. I do not want to accidentally change any parts of my old entries while adding new information. I do not like to archive entries but keep them as they are. I would like to set some headings as "read only".
How can I do that? Or how can I at least make it more difficult for me to make any accidental changes to these headings and their contents, perhaps by "locking" them somehow?
I am running Emacs 27 on Windows 10.