Master file - video not in sync with audio

I have made a video, some footages from my FUJIFILM camera and some free videos from pexels.com.

When I am looking athe video inside my timeline everything is OK. But when I create master file, in some clips video is not in sync with audio, it seems also different in different players. Inside Quicktime player video is slower, inside VLC player video is faster.

Very confusing and annoying - have anyone any idea what is going one?

thnx Marko

You may be exporting in a codec that is hard for you computer to play back.

Share > Master File >Settings > H.264

That should be good enough.

Unless you have an older Mac model that has trouble with 4K, and you're exorting 4K

I was exporting Share > Master File >Settings > H.264 just like you said...

Don't know what is going on. Anyway, somehow I finished the project. In FCPX it was in sync, in the master file there was video slower than audio, and when I upload it on YT there is now video a little bit faster than audio - don't know how that could be possible...



Anyway I have to finished it so it is like it is...

I have Macbook from 2015, so it must be OK?

It all plays back in perfect sync for me.