Notes of different durations played at the same time and in one voice

I am very new to Musescore - and to scoring music, in general, so the terms I use may not be accurate. I am scoring on guitar tablature linked to a general treble clef staff. I am trying to score a simple fingerstyle guitar melody wherein, when multiple strings are picked at the same time, certain notes, usually the lowest notes, sustain while other notes are played. I cannot find a way to edit the notes in the treble staff so the lowest note can be given a longer duration from the others. I know I can add a second guitar tablature in which to score the bass notes but, I have seen Musescore scores where it appears this was accomplished without needing to do that. One such example is a score of "Don't Stop Believin'" by Art Chaidarun found at this link:

https://chaidarun.com/musescore-tab

I have seen other scores in these forums also able to do this. Can someone detail the steps required in Musescore in order to do this?

Thank you.