How do you know which link to use?

Use “Checks For Less” if your checks say “Printed by Bank-A-Count” in the left hand margin.

Use “Main Street Checks” if the left hand margin is blank.
Each of these companies set their own security for your protection from someone else receiving your checks. One uses a restriction from making any changes. With that company, if you need a change of address (for example), you need to contact your local Community Bank office. One requires you to enter a number from the reorder form that came with your last order.
You can always contact your local office of Community Bank to reorder checks for you.