Thank you Jon,

It works, as is soupossed to.
With .MinimumScale = ThisWorkbook.Sheets("XY").Range("$e$41").Value is
ok.

I found where was the mistake: I had protected before the worksheets
(context object scenarios).
I unprotect it being on XY spreadsheet where was the first chart ( but
never thought I should go in Chart-sheet (second chart) and unprotect
that one too separately!!!! Silly me.

Next step: I had to find a way to protect the chart (series) but leave
the scale free for change. Also to make the print to not stretch the
chart and destroys square-grid (thank you for that too).

I wish you a great weekend,
Emil