MBP 15" retina freezing

so a couple of months ago my brand new MBP 15" retina started freezing after watching youtube videos. i contacted apple support and went through all the software trouble shooting and they couldn't find the source. So i booked an appointment and took it to the service center, they said that the video card switcher (that switches between the integrated and dedicated) is faulty. Although it don't think so because i ran intensive graphic demanding software and when i was done nothing happened. anyway, i submit it to them and they changed the entire logic board. i received it and been using it for a couple of months now without any issues and i was glad, then about 2 weeks ago it started doing the same issue again. i watch a video and either when I'm changing to the another video or quitting safari the entire machine freezes. i freshly reinstalled OS X and did everything that i know of still having the same issue. I don't know if it is from my machine or safari or youtube. i paid a tone of money on this machine and I'm extremely disappointed because of this issue so far. if anyone is facing this issue let me know and if anyone can help please do tell. Thanks

i also when to console and copied the messages from that time period hoping it might be helpful.

Macbook Pro 15" Retina Mid 2014