Data collection method keeps reverting to Online-offline (multiple submission)

How to configure data collection once and for all?
I’ve been experiencing and odd behaviour with KoboToolbox with regards to the data collection configuration. I set it to “Online only (once per respondent)” because it is an online survey, but it keeps changing back to “Online-Offline (multiple submission)”, even after ‘saving’ the settings.
Is this a known issue? I couldn’t find anything related to this behaviour in the community forum but it is strange. In addition, one setting or the other generate different url links to the form.
Is there a solution to this or a work around?

Welcome to the community, @gducos! Maybe this post discussed previously should help you understand why this happens:

And this post too …

Long story short: This is a feature for you to get the URL (for the proposed method). Once you have the URL for your proposed method, you can use it until you wish to have the URL for another option.

Thank you for this. However, we have had individuals test the survey that has been copied from the single submission link and they are able to submit the survey twice even tho we are using/copying the link from the single submission location. Any suggestions on this? Its really frustrating as our survey went live because it was working and now we are seeing individuals submit multiple entries

Welcome back to the community, @EllaFowler! Maybe you should use Online-only (once per respondent) as outlined in the support article Collecting Data through Web Forms.

This could be because the option selected for the data collection, is not actually selected before you copied the link. Did you check if the option in the drop down shown 'Online-only (once per respondent) before you clicked for copying the link?