fix stem directions

click on one stem, select> more> Same voice;
Press X
or see attached

That setting is indeed gone. Why would you want to change the defaults? Voice 1 and 3 stem up, voice 2 and 4 stem down.
You can still change the direction on individual notes, or on a selection of them, using the inspector.
Or indeed the X key...

Simplest way that I see to fix stem directions on a part where, for example, notes on or above third line B in treble clef have their stems going up (for unknown reasons) is to simply select all or the measure in question, then in the Inspector (F8), select the "Notes" button, then select the "Stem direction" selection to "Auto"...that should do it.

Select the first measure of treble clef, shift right arrow. After selecting all (top only) press F8 and change "auto" to "up". Then go back to your score, if you have a double note (voice 2 same as voice 1) click on voice 2 of that note and press x.
You can do the same on the base clef too (down instead of up).