Why You Cannot Change a QR Code Once It is Printed
A QR code embeds a specific URL directly into the image. If the URL changes, the code is entirely different. Once printed, the code is permanent—it cannot point anywhere else.
Common workarounds like taping over the code, including a separate notice, or mentioning changes verbally are all clumsy and unreliable. Different people end up seeing different information. There is no way to change where a printed QR code points.
The Practical Solution
Do not throw away the printed materials. Simply write a 6-digit code alongside the existing QR code.
Generate a 6-digit code for the new URL and write it on the printed material: "Latest version: 123456." That works. No app needed, no contact information required.
Handwriting might seem less polished than other fixes, but it works better. People immediately see the new code and know exactly what to do. Tape or inserts create confusion and friction. Handwritten text is direct and clear.
How to Plan Your Use of QR Codes and 6-Digit Codes
Use QR codes for information that never changes. Use 6-digit codes for information that might change. This way, you print once and can adapt later without reprinting.
Example: A flyer with your company logo and main visual never needs to change, so a QR code works fine. But a campaign landing page URL might change. In that case, use a 6-digit code for the campaign URL. If the page changes later, just handwrite a new code on the existing flyer.
Summary
QR codes are convenient, but they cannot be changed after printing. The simple fix is to add a 6-digit code—no reprint needed.
The choice is not "QR or 6-digit." The answer is "use both." Combining them gives you flexibility when things change—which they always do in real-world printing.