When you enter questions into the questionnaire, they are given their own code or numbering (Q1, Q2 ...). These are just variable labels that you can change as you wish (e.g. email...). The content of this code does not affect the data collection or anything else related to the data, as the numbering of the variables is purely an administrative function.
In principle, the numbering is generated automatically in order, but if you change the order of the questions or delete a question in between, the order is broken.
The order is restored by renumbering the entire questionnaire, which is done in the 'EDIT' – 'Questionnaire' tab, in the Advanced editing settings (the three dots icon above the questionnaire), by clicking on the # icon - 'Enumerate' . If you have previously changed the variable names yourself, they will remain unchanged.
Disable automatic renumbering:
In the 'EDIT' - 'Settings' - 'Basic settings' tab, under 'Question numbering', there is an option to turn off automatic renumbering (by default, automatic renumbering is on). This way, if you change the order of the questions or delete a question, the questions will not be renumbered automatically, but you will have to manually click on the 'Enumerate' option.