ask the help desk.
if you trying to assign solid elements to a specific layer, i'd make a group of them and change the layer manually.
if you've got lots to do you wouldn't want to do it this way.
if you're trying to make a template, i'd set up something the way you want it and save it as a set-up file.
however, i think layers (and groups) work differently, in that FeMap uses the active layer/group, so you'd need to keep changing it to get it the way i think you want !?
go back to the 1st advice, ask the help desk ...