NIB Changed how do I get it back? - Photopaint X7

My program seems to default as a circle nib when using the clone tool.  However occasionally I must click something by accident as the nib changes to a weird shaped tool of some sort.  Not knowing how to to change it back... I used the new shape tool and actually began liking it better than the circle.  That is until it arbitrarily changed back to the circle when I opened the program one day... how do I toggle back and forth, so "I" select what tool I want instead of having it selected for me...?

Thanks

R