I use a customized layout. For years I had a drop down menu option for the Company field but not it seems to have disappered. (disappeared some time ago but wasn't an issue then...). The Field is set as a Drop Down as are 8 other fieldsof the 19 fields i have on my layout.
In Define Fields, the Create, Edit or Delete drop down lists does show the Company Field, type and description. The box on the left shows there are 10,000 entries but on the layout, I do not see the downward pointing arrow enabling me to add, delete, modify the companies.