Good morning.
In the past there was an option to create custom stamps. I can't seem to find where this might be. Also is there a way to set default, label, note, dimension, legend, highlighter, arrow, box and pen settings?
You can set the default setting by clicking the Gear menu in the toolbar of the popup window, and then selecting this option:

For stamps you can try a point count with a custom shape from the properties window.