I want to encourage you to view and print the Walmart Coupon Policy. You can take it with you to Walmart and present it to the manager if you are having difficulties with Walmart accepting printable coupons. One thing that helps when using printable coupons is to print them in color because photocopied coupons (you should never photocopy a coupon) usually are done in black & white ink.

I found it interesting that if you try and use more than 40 coupons at Walmart it requires the approval of a Customer Service Manager. I have not used this many coupons before in one transaction, but I typically only use one of each type of coupon even if I have more of the same coupon. I can see if you go to the store with tons of one type of coupon and try and use all of them that the cashier may wonder where you got all of those coupons and suspect they possibly could be copied. I know there are lots of legitimate sources of coupons, but in my opinion it’s just wise to impose a limit on yourself sometimes.
Just in case, you might also be interested in reading the Walmart Return Policy.