Select subexpression in equation

[Fortin]

Right now, there isn't a perfect solution, but you can go into Home settings and change the entry mode from textbook to algebraic, make the edits and switch back. Creating a user key to toggle between Entry:=1 and Entry:=0 can make this process much less tedious and keeps the text that's already on the entry line. It's also helpful to create two more user keys: one that returns "(" and another that returns ")". This makes inserting parentheses after the fact much easier.