there's a checkbox in preferences/drawing attributes to use uniform pens and colors throughout the layout book. every drawing will then use your settings under 'all pens and colors'.
if you uncheck the box, your drawings will revert to their individual settings.
as others said, you can also set the pens for each individual drawing with 'drawing pens and colors' in the preference is left unchecked... AFAIK there isn't a way to override the Uniform Pens and Colors box for that one special drawing
HTH