Remote control stuck

I bought a TCL TV and when I press the +/- button on the remote to change the channel, it's as if I'm pressing the "source" button, meaning the TV switches to HDMI1 then 2 if I continue. I've tried using the button on the TV but the same problem occurs. I don't know where this is coming from, but it's very annoying.

I contacted the seller who doesn't know either and is supposed to get back to me, so in the meantime, if anyone has had this problem before.
Thank you.