Like everything, there's a learning curve due to the multiplicity of options. The first thing I did was copy the Bookerly font to the Koreader fonts folder on the Kobo, as I find the default Noto fonts too ugly for reading.
The second thing I did was remove the Koreader installation log file and logo which stuck out like a sore thumb in the file manager
The third thing I have to do is read the user guide...
Anyhow reading is a pleasure once I fixed the font, font size, and line spacing
Koreader
One-Click Install Packages for KOReader & Plato