A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
To answer the second question re the file listings in the Window menu;
- ✔︎ The file currently is displayed in the foreground
- ⚫︎ The file is open in the background & contains changes that haven't been saved
- No Mark The document is open in the background but contains no unsaved changes
You cannot directly change the symbols yourself [nor is there any reason to] other than by closing/saving files or bringing a different one to the front... the symbols will update automatically as you do.
Also, just to be clear, the Mac keystroke to toggle between open document windows in the same program is
Command+** which is the same action key Neo Wu referred to. I don't mean to be pedantic, but *Command+~* implies use of the Shift key because the ~ is the upper register character on that key. In this case it does make a bit of a difference because **Shift+Command+ toggles through the open document widows in the opposite direction.
BTW: On a Mac Command+Tab cycles through open applications, including Finder.