I have a young friend(30) who when she has to turn anything shouts "dotty" . For some reason she is totally unable to turn fabric, even one handed earlier this year I managed.

if I do need to turn a tube I have a set of different sized saftey pins in my sewing machine box. I use the biggest that will fit intot he channel. However for bag straps I nearly always use regular waistband slotted interfacing which irons on. Then you fold in the edges on the folds and top stitch. Gives you uniform sized straps filled with lovely stiff interfacing. works a treat!

It comes in 1" and just over 1" normally. I noticed recently, Nancy Z has something similar out but it is fairly pricey compared to normal dressmaking waistband interfacing. However she does have some narrower versions.
Becks

I make my straps like snipforfun, and it makes a nice, sturdy strap, that is easy to make.

I like using the fast turn because when you start to turn, you can catch a strip of batting or cording nd magically it pulls right through....then top stitch on both sides for a finished look...Hattie

I do this also. I like adding a layer of batting to the inside of the straps.

I use Fasturn Tubes.

I would rather save every penny for material so I use a chop stick to turn. Picked it up free at Pei Wei. Sometimes I use a large safety pin.

I got a pattern for a tote and it showed how to make the handles by cutting 4"x22", wrong sides together, press
open, one side Fusible fleece, other side of crease interfacing , iron 1/4 edges in toward center, fold over so right sides are out and stitch open side shut; hope this makes sense...but it looks great and is the way I do them all now.