I've seen an old thread from 2015 about this subjedt that says it's impossible but I wonder if now, at 2019, it's possible (Maybe with external remote? I have the T1S...)
I like to set the channels to "classic" mode 2, Throttle and roll at the left stick and Pitch and Yaw at the right stick.
The tello is a training drone for me to get flying skills before I move to other faster models and I would like it to be more "streamlined" with channels common standards.
Any suggestions?

I mean throttle and yaw on the left, Pitch and roll on the right! My bad!

Dear customer,
Through the Setting of the Tello APP, we can change the control mode in mode 2. Please have a try. But T1s is not compatible with Tello. It may not connect to Tello APP.
I hope my answer can help you. Have a nice day.