[palosanto]

Thanks Geoff.
I've turned off now the "Calculation of Setlist Duration Using Audio Files" and the total times are computed correctly whether entered manually on songs without audio or automatically in songs that have audio even if I modify those songs length manually.

I'm still a bit confused because having off that setting, if I add an audio clip to one of the songs in the set list, the time is added an I thought that it will ignore songs with audio for the running time.

So, I guess the only difference in having the setting on or off is that having it off allows me to modify it manually whereas having it on, even though I can modify it, it still computes it with the audio even though the Duration field shows the modified one ...
Perhaps the Duration field should be greyed out so that it it can't be modified manually when the setting is on otherwise the numbers don't add up.