Can't change brush stroke default

I am an experienced user, and this is a new problem for me. I used to be able to set a brush and continue to draw with it without having to go back to the menu each time.

Right now I can't (using the brush tool or pencil tool):

• Use any brush or preset and have it be anything but 5 pt. round. Each time I start a new brush it uses:

• Set a different brush as default. It always reverts to the above.

• I can't change the brush in the top menu or the brush fly out menu, it reverts to the above.

• If I try to set a new brush before I draw, it reverts to  the above.

• If I try to set the brush to Uniform, it reverts

• I can set a new brush in the brush panel, but then can't get rid of that. Nothing I do will allow me to use a basic, uniform line to draw with.

Basically to draw, I have to draw with the above brush, select the line or lines, apply a different brush. On every single line.

It's very frustrating.