How to change the control line in Mintable

The control limits (UCL, LCL) in Minitab are calculated based on your original data (μ±3σ). If you want to modify it, the most thorough way is to modify the original data. If you want to force modification, you can first select the data you want to modify with the mouse (the pink box in Figure 1), double-click the left button and modify it manually under "Text" in the pop-up dialog box (Figure 2). But don’t forget to modify the coordinate axis on the left (red box in Figure 1), otherwise it will be a joke if the data on both sides does not correspond.

Finally, it is recommended that you modify the original data, because knowledgeable people can manually calculate the upper and lower control limits based on your original data.

Hope it helps!