I'm very new to Solid Works and just doing tutorials.
I've made a part by sketching 2 circles and extruding those into a ring. Then sketching on that ring and extruding another ring.
But I can't find a way to adjust the sketch before the first extrusion. When smart dimensioning the outer ring from 100 to 200, the size won't change. However, it will display an inaccurate dimension of 200 units.
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Rebuild the part 2012 SOLIDWORKS Help - Rebuild
Regarding the other thing. Edit the sketch e.g. rmc on the sketch and select edit sketch. Add dimensions and relations 2015 SOLIDWORKS Help - Sketch Relations Overview to it. You can move the circle by dragging it if you want, if there are no dimensions or relations to it that prevents that. You probably have a coincident relation 2014 SOLIDWORKS Help - Description of Sketch Relations in the center of the smaller circle to the bigger circle and if don´t want to have the center of the the smaller circle on the bigger circle you need to delete that relation. Also take a look at how to view the sketch relations 2012 SOLIDWORKS Help - View Sketch Relations
Hope this helps.