The second way, I thought to wet the yarn in water then wind it around the balloon. After that I sprayed it. But, I still ended up with the same result. The yarn wasn't even hard after drying for 24 hours. It was stinky and flimsy. The starch actually ended up the same way as the spray glue. Didn't get the yarn stiff enough to hold the ball form.
The best way I have found was using a glue and water mixture. Everyone was saying use a 1:1 ratio but I just winged it. I made sure it felt sort of thicker and I could feel the glue in the water on my fingers. That's when I knew I had enough glue in the water. Elmer's Clear Glue is what I used. It worked perfect.
How I fixed these areas was I took my bottle of glue and just used the straight glue (as the yarn is still wet!) and tried to glue the loose pieces to tighter pieces where they crossed and met. It ended up working well once they dried. And if they are still loose ones once it dried, do the same thing.
Now, there are types of yarn that work way better with this than others. And we all know there are TONS of different types of yarn out there. I found that the plain RedHeart yarn worked best and held it's form better after it dried. Feel free to experiment with different types though. I went through a couple different brands, the Simply Soft (the light purple) didn't really get as stiff as the Red Heart, even when I used more glue in my mixture. So I would stay away from the softer yarns like the baby yarn and anything that says soft on it. They tend to not hold form very well.
Then the balloon in on the inside of your yarn ball. You can carefully take out the balloon from a section on your ball that has a larger gap and just reposition your yarn if you need to move some around. If there are any super loose sections you are try to fix it by using the same method gluing it to intersections and seeing if that works.
And there you go! You're yarn balls are done! Easy Peezy once you get use to it. It take a few balloons to get the hang of it sometimes, I know it did for me. Hope this helps anyone trying to figure out how to make these. I know when I first tired it with the kids, I was getting frustrated because there wasn't anything out there with a few helpful tips.