That annoys me too and there is no fix, even if you just use the Samsung keyboard the input selector still appears. Must be a bug.
Another annoyance is the notification sound when you plug in the charger. If you use a wireless charger it stops changing when the battery gets to 100%, fine but its changers again after a few seconds, so the notification noises keeps sounding. I was woken up in the middle of the night as my phone kept beeping at me.
I need get it rooted to fix these issues, first phone I had for awhile which hasn't been rooted and man... I didn't realises there where so many ads in all the apps and websites.