I would like to move the right barline (which is also end-line) to the left (it is just a music example of some bars and not a complete piece.)
According to the manual I should use alt-arrow or ctrl-alt-arrow for larger increments when in note-spacing mode.
It does not do that.
(ctral-alt-arrow flips my screen instead, on Lenovo Yoga)
It sounds like a system key command is overriding the one used in Dorico. There’s a solution for this here:
What you could also do is increase the minimum fullness threshold above which Dorico justifies the last system in a flow horizontally: if it’s a short system, it won’t fill the width of the page anyway. You can use the note spacing options also on this page in Layout Options to adjust how wide the non-justified bars are.