audio detach from video in the timeline

Hello,

I had a problem with my audio tracks which when gray, so while trying to solve this situation I think I have messed around some audio option...

So right now, and I do not have any idea why, my video tracks are "detached" from the video. I mean: I have the video above the magnetic timeline and the audio tracks are below. Worts, it I trim the video, the audio does not follow this, which is a problem since they look not synchronized. this is happening to all the video / audio in this Project. Event worst, this is also happening to the new files I place in the timeline.

Is there a solution for this problem?

I notice that I have never clicked a option to detached audio-video

thank you

Jose