When you change the slot in the shader editor it does not change which material is assigned to the faces. Ie you can edit a slot that is not assigned to faces.
To change the assignment of the material you need to go back to slot 1 (which is the slot that has your faces assigned) and then change the material that is assigned to slot 1 in the material drop-down.
In this screenshot if I click the red material in the dropdown it will assign it to slot 1. Note the result would be that BOTH slot 1 and 2 use the red material.
So if you want the white material to be slot 2 you would have to go to slot 2 and assign the white material.
It worked!! Thank you very much.
One question, what are the other slots for if I only use Slot 1?
Because one object can have more than one material, you can assign faces to different material slots in edit mode using the assign buttons.
In this case in the shader editor I can flip through the slots and edit their materials without changing which face is assigned to which slot.
Materials are also assigned to slots (using the material icon (see the screenshot above)
Faces are assigned to slots in edit mode by selecting them and using these buttons:
In the shader editor it is like this
The rule of thumb is that you do not assign materials to faces or faces to materials. Both materials and faces are assigned to slots (hope it makes sense), if you play around with it a bit you will get the idea.
Thank you very much, I learned a lot from this.
