When I learned to play forever ago, we had four fingers and used them right from the start. No pampering. Lesson 1 was pizzicato with open strings.  Lesson 2 was bowing open strings.  Lesson 3 was bowing fingered notes and we used all four fingers.  From that day on, open strings were taboo unless there was a very solid, rational reason for an exception.

I wonder if it comes from people who had my experience. I started the violin in the 4th grade. We didn't learn about the 4th finger until long into the year, and we were told you only use it basically to hit the highest note on the E string (It wasn't until last year that I learned the violin had positions). No one made us use it, so I didn't. I didn't quit orchestra until 8th grade, and it's funny to me how I have no memories, really, of playing or practicing or anything but the bad habits I picked up came back right along with the violin when I started playing again. The viola is just different enough to where it's acting a little as a reset, and I'm really trying to break some of those habits. I know you're right; I just got to keep using it. It kills my intonation, totally screws up my rhythm, sounds generally awful...and it's going to stay that way unless I continue to do it. 

ELCBK said
Isn't your new Viola body thicker than your violin?  You may end up needing a different shoulder rest. 

There are so many things to work on (at the same time!) when learning violin/viola... I can only concentrate on 1, maybe 2 at a time.  Unfortunately, many trad fiddle tunes I was playing were in 1st position & didn't require 4th finger, so I didn't use it as much as my other fingers (which I really regret).  Being self-taught, I finally got around to working on my pinky curling & my left hand shape/stretching/movement 2 years ago.  I'm ashamed to say that's after a 3 year combined total of playing violin & viola! 😖

It took a LONG time to overcome my habit/instinct to curl my pinky up.  I had to overly exaggerate my focus on keeping ALL 4 fingers hovering over the fingerboard & close to the strings - for what seemed like forever.  There were times I seriously thought about using tape around my 1st pinky joint - to remind me!  😳 

 

I am certainly NO expert, but found playing on the finger pads, moving the thumb for better hand balance and releasing unnecessary fingers can help with Viola playing.  Any tension kills progress. 

 

  

Thanks so much for the videos! That "plop" one in particular was really useful. I can't wait to try it. 

I was taught violin by an old-time fiddler who volunteered to teach our elementary school orchestra. Maybe that's why we weren't really taught fourth finger...maybe he was playing those types of tunes as well. 

The viola does have a thicker body. I tried a Kun-style shoulder rest with it and didn't like it. I like the "hook" of the Bon Musica, and it takes the strain off my neck. There's been a couple of times when I've had a headache when I'm done playing, and I think it's neck strain. I'm trying to be careful, trying to remember to warm up my hands and shoulders before playing, trying to really watch for tension, because I don't want this to hurt. 

Those videos you sent me lead to another one that had some hacks in it, like it mentioned your wrist is probably not going to be able to stay perfectly straight when you use your fourth finger. That's a huge relief to me, because I was really going for that.