Looking nice. I love the look of your cave, and also where it breaks into the dungeon.

Yes, the newer(larger) one is a new version. It fixes several bugs that were found with the original one, so you should install it.

That's what you say now.

That would be the Like modifer (F2). Just press F2 after selecting select by color (or fill style or line style, etc) and CC3+ should ask you to pick an entity to take the property from.

When you use click New from the symbol manager and give it a name, you should be getting a new window to draw your symbol in, size defined by where you clicked inside the view window to place the corners. This window should be closable.

The error message you describe happens when you try to close the main drawing window.

It is also important that you draw your new symbol inside that new window, if you draw it in the main drawing window, it will just be a shape in the drawing, and not a new symbol.

From your description, it sounds like you may not be getting this new window? Make sure when you place the corners for it during step 3 in the tutorial that you click inside the drawing area itself, the reference to bottom/top corner means inside the drawing area, not on top of scrollbars/title bar/etc. When your cursor is in a legal position, you should have a crosshair cursor, and the command line should also inform you that it needs window corners.

Hope this helps, if not, don't hesitate to ask for more clarification.

I'll also be happy to be informed of any mistakes you find in the manual so I can investigate and correct them where needed.