One row mode only displays one letter at a time

[Imerion]

I recently bought a Unihertz Titan qwerty phone. Its keyboard lacks a few special letters that my native language has, so I was looking for a keyboard that could give me one row of keys where I could put these, so they will always be accessible above my physical keyboard. kboard seems to fit that description well, but when I set it to display only one row I don't get a row of letters but rather one letter at a time and a key for switching between them. Choosing three rows gives me standard rows, however. Could there perhaps be an option to have a row of, say, six-seven letters also in one row mode?