When you say you "can no longer so it" - why exactly?  Is the menu gone, or when you make the selection does the change not "take"?  Have you tried the "hold F8 key at program start" to restore default settings?  If the menu is gone, try Window > Toolbars > Standard, be sure there is a check mark beside "Standard".

When I make the change in the Shape drop down it doesn't take---the eraser shape still looks like the eraser. I'll try the F8 & see if that works. Thanks

I tried F8 again & it reset my eraser tool the way I wanted it to; however, I now am missing a toolbar at the top---the one with the minimize (-) button & the close (X) button. Now what?

Have you tried F8 on startup again?  That is a rather bizaare problem.  Are you running dual monitors or some other software that might be controlling the display or placement/objects of windows?  If you right-click on the Corel window in the task bar, does it give the option of minimize, retore or Maximize?  What happens if you click on those?  

Yes, I have done F8 again & the title bar is still gone. There is no Corel bar at all at the top. I guess I'll have to reinstall. Thanks for your help.

Before you reinstall, on a long shot, if you right-click in the workspace, before you open a new window or project, it might give you the option to "Show Windows" or CTRL+SHIFT+F4.  You might give that a try.
As per my previous post, I think you might have misunderstood.  By taskbar, I mean the windows taskbar at the bottom of your screen.  It lists all the open programs, I was currious if you clicked on that icon for Corel Photo-Paint if you had any options to restore, minimize or maximize.  These options should be independent of what is displayed on the Corel traskbars.

I don't have the taskbar at the bottom of the screen, either. I'll try this new suggestion. Thanks!

I tried the right-click & all windows were already showing. The option was to Hide Windows.