Save selection keyboard shortcut

If you go under the Edit Menu you will find an entry called "Keyboard Shortcuts". In the dialog window that appears there is a pull-down menu at the top left where you can choose either "Tools" or "Menu Commands". After choosing Menu Commands find the entry for the Select Menu and click on the open triangle to the left of its name to expand it and show all of the options for that Menu. Next to the selections for "Save Selection" and "Edit Selection" you will see that there are empty areas where shortcuts and symbols would appear if there was ones for those options.

By clicking on those areas you can create shortcuts for those two functions. It took me a while to find two shortcuts which were not in use but if you click on the Shortcut field for Save Selection and enter Command-* (Control-* for the PC) and then click OK it will become a shortcut that will work exactly like the Menu item does. You will be asked to name the shortcut the first time you enter it. After establishing Save Selection I went in again and found that Command-. (Control-. on PC) worked for Edit Selection. Note there is not actually a hyphen in the shortcuts I made Just the Command or Control and the asterisk or period.