You can make the whole site public, private or members only :: collections > settings
Otherwise it can be done by user, where there are more options

Ahh, there - thanks!

I did not do it, for now just stopped when the confirmation message popped up, but it says it cannot be undone. Does that mean that I cannot set it from members-only back to public if I would want to do that at a later time?

I would have thought it could be undone. Maybe @fplanque will add insight

More thoughts on this
a) it's only a settings change in the database so in theory it can be undone
b) As a precaution or alternative a copy of the database would be exported before the change, which can then be imported to undo the change.

I doubt I'm up to testing all this out over the next few days

It means if you want to make every thing public again after that you will need (in @amoun's example) 160 + 59 clicks in the backoffice to make each post and comment public again.

@fplanque wrote earlier:

It means if you want to make every thing public again after that you will need (in @amoun's example) 160 + 59 clicks in the backoffice to make each post and comment public again.

Is this an oddity? Surely a query can be sent to the database to set all to private.

Could there be an option to have a list of titles with check boxes and then amend the selection.

It does seem odd that the change cannot be undone simply

Surely a query can be sent to the database to set all to private.

Yes and we do.

It is correct to infer that if a collection becomes private, then ALL posts should become private.

It is NOT correct to infer that if a collection becomes public, then ALL posts should become public. Maybe only SOME of the posts should become public.

Could there be an option to have a list of titles with check boxes and then amend the selection.

Yes there could but we have approx 400 more urgent tasks.

It is correct to infer that if a collection becomes private, then ALL posts should become private.

It is NOT correct to infer that if a collection becomes public, then ALL posts should become public. Maybe only SOME of the posts should become public.

OK maybe a field for original state, or dated state, a bit like item_version, so that all can be reset

Yes there could but we have approx 400 more urgent tasks.

Definitely only ideas for discussion, not a request for features

Thanks