You can use a lisp routine for it..
I have a small one to change a bunch of blocks with attributes, but it doesn´t have the option for width...
But there is another bigger routine to change a bunch of different types of selected objects, including text, mtext, attributes and attdef...
you can use it and filter only one of those types and change only one or several properties at once, it's very easy to use cause it Dialog box based... I always use it in my office.. i hope you know to load lisp routines.
The small one is edat.lsp and the other one is DDchtext... usable loading the Dt.lsp and typing "dt" after loading it.
dt.zip
Edat.lsp