Problem with 2 voices when there is only one

I often scan a partition using an outside application typically ScoreMaker.
Once the scanning is done, I transport the data as a musicXML file to
MuseScore to further edit it.
Although the partition includes only 1 part/voice, sometimes, MuseScore
assigns some notes to voice 2 in a staff. I try to correct it using edit-> voice-> 1<->2
then other notes in the same bar becomes voice 2. Problem not solved.

Q1: Would it be possible to change only a few notes selected in a bar from voice 2 to 1?

Q2: Would it be possible to force all notes in a staff to belong to voice 1 when importing
a musicXML file?