Changing modes for U1/2/3 requires switching out of U1/2/3 first. Can't remain in U1/2/3 and change mode at the same time. At least it's that way on my Z6ii.If I understand, you want to U1 to be the same as it is, except being manual vs aperture preferred. To do that just put it in U1, change from A to M and then go into the menu and save current setting to U1.