Q:

Changing exposure doesn't change lighting on objects in unity

I used this method to change exposure of the scene 
RenderSettings.skybox.SetFloat("_Exposure", 1.4);

However, my objects in the scene are still at the same lighting condition as with previous exposure value. How can i make unity re render lighting or re compute the lighting? 
I am new to unity so apologies if this is a noob setting. 

A:

From Unity's documentation: 

If you change the skybox in playmode, you have to use the DynamicGI.UpdateEnvironment function call to update the ambient probe.

Try adding it after your code:
RenderSettings.skybox.SetFloat("_Exposure", 1.4);
DynamicGI.UpdateEnvironment()

