Shirring trouble shooting help please

I am attempting shirring on some viscose. I have never done it before and one of my wips is the tempo dress where I totally bottled it. So once I master this, I can finish that for the summer. This time I am making the Style Arc Asha dress. The elastic is hard to get through the bobbin slots. On my first attempt it came out as soon as I started sewing, then looped on the back. 2nd attempt, it came up really tight, but is hard to pull through the machine and pings back as soon as I cut it. I have watched a couple of YT videos which indicate that tightening the tension helps, but I think that my issue is at the bobbin end because none of the videos had the elastic pinging back! My bobbin casing does have a little screw in the side. Am I going to muck everything up if I loosen that a little? 

Hi Karen, when you have finished sewing a row of shirring stitches make sure to pull the bobbin elastic out until you have some slack. As it's still tight when you go to snip the threads it will ping back so you need to make sure it isn't being pulled and has lots of slack before you snip it.

Thank you I am going to have another go probably tomorrow so I will do that.