How to change the color of an existed entity ?

My dxf is consisted by two entity.

one is a simple line which color is white

another is a special group entity (which is inserted by "Insert"),the color of this group is white

I want to change color of line to red .
and change the color of group to blue.

BTW, the two entity lies on same layer currently .

How can I do that ?

Thanks very much . Welcome your idea sincerely.

Use Main menu:

Modify-> Attributes

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For a block, you should select the block in the block widget.

Use the button "Edit the active block in a separate window" to edit the block.

Then, you can change the attributes there.

All copies of the block will show the change.