Hello,

I apologize if I am not following the usual protocols for bug reports.

This is somewhere between a bug report and a feature request.

The function `reftex-change-label' defined in
`lisp/textmodes/reftex-global.el' asks for the label you want to
change (`from') and what you want to change it to (`to'). The default
value for `from' is the label under point, which is good. I think the
initial input for `to' should be this as well (or rather, whatever was
entered for `from'), since usually, one just wants to make a small
change.

This is a trivial edit. I have attached an appropriate patch for the file
https://git.savannah.gnu.org/cgit/emacs.git/tree/lisp/textmodes/reftex-global.el?h=emacs-28.0.91

It could be better to add a customizable variable to control this
behavior, but I am not familiar enough with the reftex code to provide
a patch for that now. However, I think the new proposed behavior is
better, and I doubt that any existing code depends on the old
behavior.

Best,
Joj