If you scroll down the pane, there should be a Length Semantics settings below the grid.
I am a bit surprised about "rarely used settings". I hardly know any table without a string typed column. My experience with Oracle applicatioEven DB2 for LUW knows the string units specifications octets and CODEUNITS32. Maybe this is a specialty of Switzerland; and I cannot understand for sure, why the applications do not change to the char DB setup with their next DB upgrade.
I can live with that. Now, that I know, I should look for rarely used settings outside the grid where the rest of the settings is located. ;-)
I am no sure whether I am doing something wrong or I have stumbled over an issue.
I am creating a table containing varchar2 attributes. When setting up the first column, I was asked whether to have it byte or char. In the following one, I was not asked and I could not find a way to make them char afterwards.
For me, it also is strange that the grid does not show the char definition one can see in the SQL code.