>>>>now its supposed to change all lines color within the layer when i change one line color?
No, you have to change Color property of the Layer, but not only one line on that Layer.

I see you view your drawing inside viewport on Layout, so check also are there any Viewport Overrides for the viewport you are using to look at the Model:
- In Layout switch to Parer Space (PS command),
- Select viewport, right-click on it
- Select "Remove Viewport Overrides for all Layers" from context menu