change subscript and superscript to require braces in org mode

settings/org-settings.el

@@ -245,6 +245,7 @@ Example defines
   :config
   (setq org-startup-folded nil)                    ;; nil = showall = #+STARTUP: showall
   (setq org-startup-with-inline-images t)          ;; #+STARTUP: inlineimages|noinlineimages, show inline images when loading a new Org file
+  (setq org-use-sub-superscripts '{})              ;; braces are *required* in order to trigger interpretations as sub/superscript, see also `org-export-with-sub-superscripts'. C-c C-x \ (`org-toggle-pretty-entities')
   (setq org-image-actual-width '(600))             ;; image width displayed in org
   (setq org-tag-persistent-alist '(("ignore" . "i") ("noexport" . "n")))
   ;; todo see also org-todo-keyword-faces and org-superstar-todo-bullet-alist
@@ -671,6 +672,7 @@ usage: #+HEADER: :prologue (mpl-prologue)
   ;;(add-to-list 'org-export-filter-latex-fragment-functions
   ;;             'my-org-export-filter-hyphen-shy)
   (setq org-export-with-smart-quotes t)  ;; OPTIONS keyword, e.g., "’:t".
+  (setq org-export-with-sub-superscripts '{})  ;; OPTIONS keyword, e.g., "^:{}".
   
   ;; http://permalink.gmane.org/gmane.emacs.orgmode/93971
   ;; https://emacs.stackexchange.com/questions/30575/adding-latex-newpage-before-a-heading/30892