When you use the Color option of the Set Property Alterations dialog box, the colors of objects change to the color you specify. However, if the queried objects include blocks whose color is set to BYLAYER, the objects in the block retain their original color. To have them use the color you specify, change the block color to BYBLOCK.
To change the block color in your current drawing
Select objects: Select the objects in the exploded block
Enter property to change (Color/LAyer/LType/ltScale/LWeight/Thickness)? C
Enter new color <varies>: BYBLOCK
Enter property to change (Color/LAyer/LType/ltScale/LWeight/Thickness)?
Press Enter