Couplers randomly opening- PLEASE HELP!

Pry off the coupler armature.  Bed it up.  Put it back on.

Jon

Wrap a smaller rubber band around just the shank of the coupler, not the axles!

@KOOLjock1  They are not bending, the problem is still occurring. They are plastic armatures.

@Artie-DL&W  I have a Latex allergy, so the bands that I use do not contain latex, and I have not found any Non-Latex bands that are small enough.

Another option is to use twist ties, or small wires, or plastic wire ties, which is what I prefer. Get the smallest available, tighten it around the shank and tab, and cut off the excess. It’s very unobtrusive.

@Artie-DL&W  Thank You! The problem is fixed.

I cannot believe that I did not think of that!

You’re welcome, glad it worked out.

Artie in a nutshell. Polite, succinct, helpful. Sorry he’s gone.
An aside - if OP had threaded his rubber band under the axles, it appears his fix would’ve been satisfactory.😊

I know the OP 's problem has been solved, but just wanted to add that I have also experienced this problem with several cars.   If the coupler button is made of plastic, then you are not going to be able to couple and uncouple it with an electronic coupler, so you have to always connect the car to the next car by hand.

For me at least, it is far easier for me to do this by keeping the coupler closed, and then lifting the car up and setting the coupler inside the adjoining coupler, than bending down, squinting to find the coupler tab, and trying to open it with my fingernail.   Because this is how I do it, I solved the problem of the coupler coming open by tying the coupler tab permanently shut using a black tie strip from Harbor Freight (instead of a rubber band) and then clipping the end of the strip off really close to the buckle.   

The black tie strip blends right in with the black coupler and you can barely see it.   So, the problem is permanently solved.

Mannyrock