Problem with fade text and video sync

Example:

I’m making videos and I found out how to make fade text using this tutorial https://www.youtube.com/watch?v=vhyjkFSTqC4, but when I saw my video in the part where I put text I wasn’t in sync with the video even if when I edited it the copied part of the video was right above the video.
Why does this happen?

You can see double in the video at 6:35

Can you post a screenshot of your Shotcut timeline where the sync issue is happening?

also when I split at playhead and play the bit i’m editing it lags alot

And the duration of the fade in fade out video has to be 1sec or 0.24 or less,
all the numbers in between dont work.

Are these lots of bugs or am I doing something wrong.

It happen everytime I copy a segement of the video and paste it above on a different timeline.

This is normal on many lower specced PCs and laptops. It will export just fine.
Remember anything you do on the timeline is being rendered on-the-fly when you playback in the editor.
This requires some good horsepower if you want smooth playback (in the editor)

SirgPorg, it looks like you’re doing things correctly to me. The finished product (the video that you posted) looks in sync, but I don’t know the source well enough. Is the exported file in sync?

As Steve_Ledger said, the editor being choppy/out of sync is normal; on one of the computers that I edit on won’t even play one clip smoothly, and it’s more and more out of sync when I preview it in Shotcut the more tracks I add.

However, while the “live preview” might be out of sync, the individual frames should still be being rendered properly. My workflow for editing is to drop a clip in the timeline, and then advance through the frames where transitions happen to make sure that frame-by-frame there aren’t any jumps or weirdness. You can advance frame-by-frame by pressing the up and down arrows at the bottom-left of the preview; in your screenshot the current frame is 00:00:21:16.

This timecode stands for HH:MM:SS:FF (hours:minutes:secons:frames), 21 seconds and 16 frames. I’m not an expert but I’d be willing to bet that the reason you can’t have a fade “between .24 and 1s” is because you’re editing in 24 frames per second.