brightness error
When I take the clip and put it on the timeline, some of the clip exposure turns strange (gets brighter. see the first photo) in the preview window. I have tried opening the new project and add the clip that went brighter first onto the timeline. It looked fine but the other clips that were okay went darker.(See photo 2 and 3) I've also exported the video but it still looks the same. 

How can I solve the problem? Thank you.