Please please please do not take the spools off the overlockers to use on the other machines. Or if you do take a spool off - rethread it when you finish. It’s really not on leaving the overlocker bare and leaving the rethreading to someone else.
I spent over an hour rethreading last night. I will buy a collection of new spools and bring to the space this weekend (black, white, grey) so that we can have each machine loaded and ready to go without cannibalising each other.
Same goes for if you change overlockers to 3-threads - put it back to how you found it - 4-threads.