Why can't I change my keyboard language input?

[AC Question]

I realized that I can't change my language input for my keyboard. I actually knew about this like about 1 or 2 months ago but i thought maybe it was only a problem that can be solved by just restarting the phone, and because I was in rush, I used my friends phone and I forgot about it. Now, even after a few month (and of course the phone had been restart for few times) the problem is still there. Please help me. Thank you in advance.

 

[Az Androiddev]

It would be helpful, if you could tell us, which keyboard you're using and what you have already tried to fix the problem.

 

[leomatt93]

I'm using samsung keyboard, galaxy S5. I've tried restarting the phone and i've re-downloaded the language input. Nothing's change.