If you want to change any standard texts in Limesurvey you need to make an adaption to the translation, but be aware that with future updates your modification might be overwritten.
Help us to help you!
Provide your LS version and where it is installed (own server, uni/employer, SaaS hosting, etc.).
Always provide a LSS file (not LSQ or LSG).
Note: I answer at this forum in my spare time, I'm not a LimeSurvey GmbH employee.