After you get the clamp screws down tight as you feel comfortable,
secure them somehow so they don't come loose.
I use a zip-tie through the holes in the end of the handle.
If you do not have a hole in the end of the handle, put one there !!!
Also, do you have holes in your transom bracket of the motor so you
can bolt all the way through the transom ?? If not, put some there.
A motor that is firmly bolted through the transom not only ensures it stays put
in use, but, resistant to a crook wanting to snatch your motor and run off with it.
Then, hook up a transom saver bracket. Several threads on making your own
as well as store bought ones.