A same scene in Preview and Program doesn't display the same thing

[Julot]

Hi!
I'm having an issue where the Preview window is showing something different from the Program window. I already checked that the resolution settings match, and they do. Honestly, I’m not sure what to do next. Does anyone have any ideas?

If this is not clear, the text is bigger on the left window.
Thanks in advance !

 

[JonathanC09]

In the 3-dot menu next to the transition button, disable the option to duplicate scenes and duplicate sources.