Gramps, Reports, Error Message

Since January I run Gramps v. 2.2.8. which I downloaded with Add and remove SW.
Anytime I produce a Graphic Relations Report (Reports/Graphs/Relations Report; All terms in this message are translations of my own from the Swedish language version.) I get the Error Message: "The information contains characters which can't be converted into Latin-1. This characters were replaced by question marks (?). In order to show the correct characters, please uncheck the option Latin-1 and try again."
In the Gramps database are several persons whose names are spelled in Czech, Slovenian and other Slavic languages, e.g. František or Miša. In the report they are spelled Franti?ek or Mi?a.
Where do I "uncheck Latin-1"?
I tried without any success to change the settings in the SCIM platform.