You really need to get a thorough understanding of pen assignments in SP before you start monkeying around with them. Especially if you are setting the default settings in System Options.

1. What you see is not what you get. What you see on the screen is initially determined by the Color Assignments, not Pen Assignments. So you may have a color assigment as blue but a pen assingment as red. You will see blue on the screen but it will print red.
2. Learn what the default pen assignments are for various components. These can be found by selecting Pen Assignments and looking at the various default settings. Note that these settings only affect new items that are drawn. They do not affect previously drawn items. So if you change a pen assingment for lines it will not affect any previously drawn lines. Also, once an item has been drawn you can edit it and change the existing pen assignment.
3. Symbols use the pen assingments of the components that make up the symbol. So if you create a symbol that has some lines with pen 2 and other lines with pen 3 those settings are retained in the symbol. I believe that all stock symbols come set with pen 2 so if you change pen 2 it will affect all symbols. Again, you won't see this on the screen but only when you print the drawing.
4. Just like all settings in SoftPlan, there are two areas where you make the settings changes. System Options affects any new drawings you create after making any changes. It does not affect any drawings already created. Drawing Options only affects the current drawing and no others. Use Drawing Options for testing your pen assingments and then when you get them the way you want them make the same changes in System Options. If you then want to import these settings into drawings you have already created you can use File-->Drawing Options-->Pen Setup and select Reset to System. You will have to do this for all existing drawings that you want to change.
5. Pen assignments for walls and beams are assigned using the Wall Definition and Beam Definition dialogs. Changes here does affect all walls and beams in the drawing, including those previously drawn. I would start out by drawing a series of lines on a blank drawing. Assign each of these lines a different pen number, 1-16. Throw in a few walls, symbols, etc. Do a test print and see how they look. This will give you a starting point to see what the current settings are.