Playback wrong

Sill: Then, if you had set it to pizzicato (staff 1 voice 1 in measures 145, 146 and 147, the first would have been enough), you need to unset it again, set to 'normal', at the place where you want it to stop (same staff and voice, measure 186?).
Check my attachment above, where I did switch back to normal in measure 186

Once you mark it as "pizzicato", everything else will continue as long as you do not mark it as "arco" (or "tremolo" or "some other thing".) Option specified as "normal" in "Staff Text Properties" dialogue box.
There is no need to write "pizz" on each note / passage.

Briefly:

1. Make a staff text (eg: "arco");

2. Right click on it, and select "Staff Text Properties" option;

3. in Staff text properties;
   a. tick same channel in dialog box
   b. select "normal",
   c. click [OK].

Looking at your 'updated file', it looks to me like you need to make a pizzicato roadmap for that first violin part.
In other words, in MuseScore, violin normally starts out arco (as your score does).
So...
At what precise measure (and on which note in that measure) do you wish pizzicato to start?
Looks to me like it's the first note in measure 144 - because that's where the Staff Text Properties first changes to pizzicato.
At that point the violin merrily plays pizzicato -- for the duration of the score, until you tell it to stop by putting in another staff text... so.....
At which precise measure (and on which note in that measure) do you wish pizzicato to stop?
That's where you put the next staff text, and change the channel back to normal (i.e. arco) using Staff Text Properties.
Now, the violin merrily plays arco (i.e. normal) -- for the duration, until you tell it to stop by putting in another staff text (maybe this time for tremolo).
Repeat this procedure until the end of the score.

BTW:
Check out measure 332. Why place the notes in voice 4 (where they play arco); and then, in the very next measure, return to voice 1 (which is assigned the pizzicato channel)?

Also be advised that in Staff Text Properties voices, as well as channels (e.g. tremolo, pizz.) can be assigned.
I mention this only because in the first beat of measure 338 voice 1 plays pizzicato while voice 2 simultaneously plays arco.

Regards.