1.) Click on Coupons Under WooCommerce
2.) OPTIONAL: Search for the coupon you'd like to edit or update (this is found in the top right area of the coupons list page):
3.) Either click the coupon name or click edit when hovering over the coupon (as shown below):
4.) On the Edit Coupon page, click the Usage restriction tab (shown below):
5.) Add the user's email to the Email restrictions field, shown below (if more than one user qualifies for this coupon, separate with a comma):
6.) Once the new email is added to the Email restrictions field, click Update to save your coupon.
7.) REMEMBER, if the user qualifies for multiple coupons make certain to add them to each coupon.