For those that glue baste.
 

I glue (Elmer's school glue in bottle) baste using a roller so every inch of my quilt is together. When the glue dries it sometimes wrinkles the quilt front and back. To get rid of the wrinkles and get the surface smooth again steam iron it. The steam loosens the glue and everything is smooth again.

I only use Elmer's, though not as much as you're using. It's not necessary. What you're doing is not allowing a little give when you quilt it. I lay my backing on carpet and pin all around, then I lay my other two layers and Stretch them out. I will glue one of the ends about a foot deep. I will use a long circle 8 motion trying to have at least 4 inches of negative space. I then pin that portion down and roll the top and batting, separately, to that point and begin again doing about 12 inches. When you have 100% coverage and no negative space your quilt won't have give.

I want my quilt to not shift or move from the layers at all. I get excellent results from every inch being held together. No puckers, no winkles, and no stretching and no wavy borders. I won't get on the floor to baste a quilt. When the glue dries completely sometimes the glue will draw up causing wrinkles. The steam iron smooths it out perfectly. I use a roller bottle so the glue rolls goes on very thin and evenly. I use to use a paint brush but the roller bottle is so much better. My quilt is like quilting paper. Nothing moves out of place. Save me so much frustration and I never worry about puckers or excess fabric when I stop and start at a seam.

After stitching it into place, it’s soaked in the tub several hours in hot to warm water. Agitated every .5-1 hr. Then washed and dried.

I have been glue basting for a long time. I don’t paint it on or dilute and spray. I drizzle it from the bottle in a grid or some pattern that mimics pin basting. As in glue every 4 or so inches. Sometimes it looks wrinkled but I have never gotten a pleat. I wash the finished quilt in machine on warm and sometimes pre soak for 15 minutes and am always happy with the result.

Question:
Do you secure the backing to glue the batting to the backside piece, then glue the top piece to the batting? Or all layers together?

I’ve done it both ways depending on my
mood. The way I do it is very forgiving and easy.

I glue back to batting then top to batting. Works best for me this way. I had one glued and put away and a few months later I didn't care for the backing after all. I used steam and the glue loosened and I was able to remove the backing. Didn't cause any problem at all.