Sketcher dims precision and Diameter dims

After using the customary search tool and not finding exactly what I was hoping for, I have yet a couple more questions.  How can I change the amount of digits shown in sketcher and it will always be the same here on out?  I do not want to have to create some template either.  I looked in system options and did not see anything.  I thought document settings were for things that applied only to the document at hand.  Also in sketcher, do I always have to dimension an arc or circle with a radius then have to come back and do a "show as diameter"?  That is frustrating.

Thank you

SolidworksSketching