In Calc, I go to Data Validation and create a list of ideas, but trying to determine how to set a default value.
I think there is also a way to put the list in a drop down menu, but cant remember how.
Try to remember how to use google - this time I give you the secret words:
libreoffice calc data validation list
and I don’t think data validity is the right tool to set a default value, because it is only active when you enter a value.
If you never enter something the cell will remain empty. You may put your default first in the list to speed up proceeding.