I've got a Samsung Note 9 and I think in the past I used to be able to edit the personal dictionary to include the names of my friends, business names and abbreviations.
Now I cannot locate the option and it is very annoying to find the Samsung OS or autocorrect changing the names of my friends to something entirely different.
I can't even get samsung phone to autocorrect simple common spelling errors such as "vorrection" (correction), "fo" (go), "ne" (me) .
Not sure what is happening but this just encourages me to consider buying another phone rather than Samsung.
