Material choice does not update render view

Question

It seems that switching from one material to another in Object mode is not updating the real-time render view or the full "Render" output window with the newly chosen material - instead, only one material in my list is still being used.

In attached screenshots "peep blue 01" is the initial selection and render output - it's a light blue material.

When going to the Materials tab and choosing "peep blue 02" I see the correct Preview for that darker and more glossy material, but the change is not reflected in either the real-time render view or when I run a full Render in a new output window for that object. It did show correctly in renders when I first created the material, but switching back is not taking effect.

I figure this is something simple, but this amateur Blender user is kind of stumped. Advice welcome!

Answer 1

Answering my own question, because I happened upon it in another post:

How can I swap Textures and Materials

To change the active material assignment, I noticed a couple options:

Option 1:

1. Go into Edit mode for the object
2. Choose your desired material from the Materials list
3. Click on the "Assign" button to apply that material to your object

Option 2:

1. Go into Object or Edit mode for the object
2. Click the black down-arrow to the right of the Materials list, a menu opens below
3. Choose "Assign Material" -> {name of desired material} and it will apply that material to your object

Somehow in my "beginners" reading and tutorials, I missed this detail. Leaving this answer here in case it's useful for others.

Answer 2

Your answer to your own question isn't quite complete, so this attempts to round it out a bit.

You've given Suzanne two material slots. Slots are a mechanism for assigning multiple materials to a single object. Slots are (mutually exclusive) sets of faces, each associated with a material.

When you assign a material to an object, it is given one slot automatically, which contains all the faces of the object. New slots, beyond the first, are empty on creation. You can add faces to a slot by selecting them in Edit mode, and assigning them to the active slot with the button beneath the slots list.

You assign a material to a slot by making a slot active, and selecting or creating a material in the materials dropdown beneath the slots list.

Deleting a slot containing faces assigns the faces to the next slot up, unless it's the top slot, in which case the faces are assigned to the next slot down. Deleting all slots reverts the object to a default material.

(You'll find that slot assignments are not updated in a render until a return to Object mode)