Default settings for strings and numbers

How do I change the default settings on SQL Server so that; when I create a
new table in EM or import a table from Excel, I will always get varchar(100)
for any string instead of nvarchar(255), and change the default for numbers
to numeric(19,6) instead of float(53)?
Thanks.
ArcherNo, Enterprise Manager does not have any provisions to change such defaults
for datatypes.
Anith