Proper way to substitute audios?

Hi, I am substituting some audio files for other audios, but in previews and playing directly in the timeline, the old audio keeps playing instead the new one. I Substitute by changing audio from file, also importing in the edit view. Also delete the old audio from the slide and insert the new one, but the old audio "wins". What can I do?

It happens in some slides, in others not. Can´t find the logic.

Thanks