It is because of this configuration.

Is it possible to change the DEFAULT options. I never use the default to record as complete after a week. It would be great if I could change the default if possible?

Yes it is possible to change it. Just chnage it using the options available and save it.

Sorry, I mean change the default, so that any new projects have the new settings - is that possible?

Sorry even I am not aware if we have that option.

No worries -  I guess the alternative is to have a template project with all the options you want set and then copy that when you have a new project.

StartDate: When the respondent first clicked the survey link.

EndDate: When the respondent submitted their survey OR last time the respondent interacted with the survey.

RecordedDate: When a survey was recorded in Qualtrics.
Because of incomplete responses, the EndDate and RecordedDate may disagree. The difference can be determined by the time you select for incomplete responses, or by the default of seven days.

Setting a Time Frame for Incomplete Survey Responses: 

1. Open Survey options in the Survey tab.
2. Go to the Responses section.
3. Select what you’d like to happen when the deadline is met.
4. Select a time frame.
5. Choose when the time frame begins counting down.

Source: https://www.qualtrics.com/support/survey-platform/survey-module/survey-options/partial-completion/?_gl=1*10wo19g*_gcl_au*MTg2MjkxOTU1LjE3Mzc3MjUyNzA.*FPAU*MTg2MjkxOTU1LjE3Mzc3MjUyNzA.*_ga*NDQ2ODI3MTU2LjE3Mzc3MjUyNzI.*_ga_Z0RM4JK167*MTczOTUzNjE1MS41My4xLjE3Mzk1MzcyNDIuMC4wLjUwNDk4NDM5OQ..*_fplc*cSUyRm9UOVhoSWlEWlNaRDYyYiUyRlBaUE5uNWFvajNEZnk3T3VIY0NsR05wN2tMMiUyRkE1R0lYOVNCTVB0VlpNZ2tJdFdJMUNjblFTeHJFbUwzZ2RhSHFvVlU1dzUzJTJGNmtQd1hwJTJGajZqQjVDM2YlMkJ4eEpXNzFqOWZYM1Q4TlpEMWxnJTNEJTNE#SettingThePartialCompletionTimeFrame