You can change the linetype of an object by
reassigning it to another layer, by changing the linetype of the
layer the object is on, or by specifying a linetype for the object
explicitly.
You have three
choices for changing the linetype of an object:
Reassign the object to another layer with a different linetype.
If an object's linetype is set to BYLAYER, and you reassign the
object to a different layer, it acquires its linetype from the new
layer.
Change the linetype assigned to the layer that the object is
on. If an object's linetype is set to BYLAYER, it acquires the
linetype of its layer. When you change the linetype assigned to a
layer, all objects on that layer assigned the BYLAYER linetype are
updated automatically.
Specify a linetype for an object to override the layer's
linetype. You can specify the linetype of each object explicitly.
If you want to override the layer-determined linetype of an object
with a different one, change an existing object's linetype from
BYLAYER to a specific linetype, such as DASHED.
If you want to
set a specific linetype for all subsequently created objects,
change the current linetype setting on the Properties toolbar from
BYLAYER to a specific linetype.