I am an amateur coder - I really only do a few things to make my life easier. I set up Google Forms and Spreadsheets for tracking discipline problems in different grades at my school. I wrote a short script that notifies the appropriate people by e-mail of any submission and that can filter and create reports about selected learners.
Because I do DIY coding (English and French teacher, so I did not study programming), I often come up with some improvement that should have been obvious from the start. I really do not want to copy and paste the script improvement into every spreadsheet's script editor. I have copied this script as a stand-alone file in Google Drive but I cannot insert it into any of the spreadsheets because the gallery only has access to published scripts/apps. Is there a way around this? I've seen mentions of using libraries, but I have no clue even where to begin. It feels a bit silly that you can create a script as a stand-alone in Google Drive but not actually use it.
Any help would be appreciated.