I've just gone through the same problem. I worked out that I must click on the 3 bars on the right of the page and click on "Logout"

I then re-logged in using my Memo encryption PW.

I instantly saw the memo message, with the password matt-a created for me.

I logged in again with my normal 'Posting key' and then used the pw on my friends computer (No point in trying to do it on yuor browser, use only the browser/pc or phone of the person who will be using it.