"I am wondering why the alignment of columns when using my old Dell are Not as good as those when used my iMac and new dell."
This has absolutely nothing to do with MATLAB.
It is because you are not using a fixed-width (aka monospaced) typeface in that text editor.
"How can I fix this problem?"
Change the text editor to use a fixed-width font, e.g. Consolas or Courier or PT Mono (which is what your first screenshot appears to show, whereas the second screenshot appears to show Arial, which is a variable-width typeface).
In MS Notepad change the font via menus Format -> Font... and then select the font.