It depends on what you are trying to investigate with your questionnaire. As a general rule, all questionnaire items should be linked to your research questions (break them down and simplify them). In qualitative research, these questions tend to be more open-ended, and you expect participants to provide long answers. If you are using a rating scale, you can develop your own from scratch, but need to validate it (test it with a sample and then verify that the scale is getting the information you want to get - you can do that with exploratory factor analysis) - if you are going to use a validated scale, I suggest you do not adapt the questions, but if you do, you will need to validate the adapted scale for higher accuracy.

what is your field of study and for what purpose do you want to use/adapt in a questionnaire??

@Anastasia I want to conduct study on Credit Default Swaps (CDS) by taking responses from risk managers, and adapting questions from a study on derivatives.

Tabassum S., I trust you have progressed with your study.

I will also be undertaking qualitative research, and will likely be adapting survey questionnaires from reputable sources. However, relevant citations with supporting rationale for the adaptation will be submitted for Ethics approval.

In agreement with Anastasia's comment on the use of validated scales, particularly in quantitative research.

Yes, there is slow progress. Trudy Leong thanks for your valuable contribution to the question.