I have a survey with 20 questions and I want to show the respondent an overview of his answers to each question at the end. For instance which question he answered correctly and in case of the wrong answer show him the correct answer.
You will need to read about Expression Manager. It allows you to access responses given within the same questionnaire in previous answers and display them, also you can check if it was the right or wrong answer and display text accordingly.
However, without reading about Expression manager (Joffm already gave you links to the manual where you can find further reading material), you won't be able to create a report like that.
There are plenty of examples on how Expression Manager works in the manual. The BMI calculator example is probably a short and pretty good example for what you want to achieve.
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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.
The following user(s) said Thank You: DenisChenu, Hajarha