Then there is no need to convert your Texts to Mtexts, so the following should change the similar text strings automatically that reside into your current active space.
(defun c:Test (/ sel lst int ent)
;; Tharwat - Date: 20.Apr.2021 ;;
(and (or *inc_* (setq *inc_* 1))
(setq
*inc_* (cond ((getint (strcat "\nSpecify increment number < "
(itoa *inc_*)
" > : "
)
)
)
(*inc_*)
)
)
(while
(and (setq sel
(car (entsel "\nSelect Text to add increment suffix : "))
)
(= (cdr (assoc 0 (setq lst (entget sel)))) "TEXT")
(setq int -1
sel (ssget "_X"
(list '(0 . "TEXT")
(assoc 1 lst)
(cons 410 (getvar 'CTAB))
)
)
)
(while (setq int (1+ int)
ent (ssname sel int)
)
(setq lst (entget ent))
(entmod (subst (cons 1
(strcat (cdr (assoc 1 lst))
"xPos."
(if (> 10 *inc_*)
(strcat "0" (itoa *inc_*))
(itoa *inc_*)
)
)
)
(assoc 1 lst)
lst
)
)
)
(setq *inc_* (1+ *inc_*))
)
)
)
(princ)
)