Change glyph for PDF Checkbox with Check Style Cross

[micro]

When inserting a PDF form checkbox, with a 'Check Style' of 'Cross', the size of the cross can be controlled by the font size in 'Content Properties', which is great.

Question: is there any way to change the glyph used for the cross? I'd prefer a straight clinical 'x' rather than the stylised 'x' used by Scribus.

If this can't be changed, no big deal. Just asking.