I am creating a new testpoint symbol. Simply a pad with a silk screen circle around it. When I draw the circle (Add/Circle on pkg geo/silk top) I can not resize it once I end the circle command. I have tried edit/change, edit/vertex; edit/delete vertex, etc...... The only way I can find to change it is to delete it and draw it again. I have found the same thing to be very cumbersome when trying to edit the silk or assy outline in pkg/geo. Sometimes edit/vertex works, sometimes it doesn't.
I am using general edit mode and have selected the correct filters.
I am not aware of any way to change the size of a circle once it is drawn. The only thing Edit - Change allow you to do is change the subclass and/or the width of the line used to draw the circle. I used Mentor Boardstation for years and it had the capability to change the size of a circle. As far as editing vertices I've found that Edit - Vertex applies to lines not shapes or circles. If you have a shape drawn you can select the shape and then change the shape by moving vertices or adding new ones. Perhaps someone else can tune us both in to a feature of which I am unaware.
One of the new features added to the 16.6 release is the ability to change the radius of an instantiated line drawn circle. You hover over a circle then use the RMB to access the 'Change Radius' command when in the General Edit App mode.
16.6 updates for Allegro PCB Editor can be fouind at the following location