Set the DEFAULT view on Customer's ticket list

is there an option to SET the DEFAULT, say, ALLOWS show UNRESOLVED

There is not currently a way to do that.

I know…
can you please ADD this option - or remove the word DEFAULT…
who wasn’t to see closed tickets if there are open tickets…

Made a note on my end about your request. I just double checked and “Default” is the equivalent of All. Then you can filter it from there.