There are 2 options to change the name of your survey :
1- Go to “edit”, click on “survey settings”.
You can change the title and/or the header of the survey display
Don’t forget to validate your options !
For your information :
The TITLE is displayed in “My survey”, in the application.
The DISPLAY HEADER title is the title your respondents see, directly in your questionnaire.
2- In "My surveys", click on the three points at the right side of your survey and click on "Rename". Put the name and "Validate".