To select an individual order, just click on the line that contains the order. It will be highlighted.
To select a range of orders, click on the first order you want to select, hold the SHIFT key down, and click on another order. Every order from the first to the last will be selected.
To select multiple individual orders, click on the first to highlight it, hold the CTRL key down and click on each of the other orders you wish to select. In the screen below, the first and last orders have been selected in this manner.

Once you have selected the orders that you want, check the boxes in the Operations section to pick the operations that you want to perform (if an option is grayed out then you have not enabled it in the Preferences function – note that if you change preferences you must close this window before the preferences will take effect).
Note that the Is To Be Printed column is not used to select which orders to work with – this merely displays the setting that is checked in the order in QuickBooks. It cannot be changed in this window. You can use it to filter which orders are shown by dragging the heading to the group heading.
Click the Process All button (to process all orders listed) or the Process Selected button (to process just those orders you have highlighted). The program will perform the operations, and open a “results” window to show you what was done.