Each entity gets its attributes (color, line weight, line type) from:
- the layer it is on (By Layer)
- the block reference (By Block)
- uses its own, fixed attributes
If you want to insert multiple instances of a block with different attributes, set the attributes of those entities to "By Block".
For example, if you have a block containing a rectangle with its color set to "By Block", you can set the color of one block reference to "Yellow" and another one to "Blue" to create one yellow and one blue rectangle.
You can also insert one rectangle on a green layer, setting the color of the block reference to "By Layer" to create a green rectangle. In this case, the entity gets its color from the block (By Block), but the block gets its color from the layer it is placed on (By Layer). If the layer happens to be green, the entity is shown in green.