If you like, once you format the autoshape to your liking,
right click and click "Set Autoshape defaults". Future
drawings will have the same attributes (behind text, in
front of text, etc.). Click View > Toolbars > Autoshape,
then click Tools > Customize. Click on the Autoshape
category you want, and drag the preferred shape to its own
spot on any toolbar. This will save you some clicking.
I would format the shape to be in front of text (behind
text needs to use the object selection arrow on the
drawing toolbar in order to move or edit, which is
probably an unnecessary step for your purposes), with
colors and lines set to No Fill. Experiment with
different types of circles, etc., and have a look at the
freeform line tool if you want a hand drawn look to your
circle. Press the Alt key to have more control while
dragging to create the shape or when moving it. Also,
click once to select your drawing object, then press and
hold Ctrl while using the arrow keys to nudge the picture
into exact position.