Don't be fooled by the seeming addition of the word "trouble" to the verb "have". Just learn to treat the two words, "Have trouble" as if they were a single verb. That way you can have trouble the same as you can enjoy, hate or practice:
- affording things
Learn to practice and conjugate "have trouble" and use it spontaneously at your first opportunity. ;-)
Other verbs don't go with "..ing" and you will learn to use them separately.
*Note: It is bad pedagogy for a teacher to introduce to a student two things which mustn't be confused with one another; neither in the same breath, nor on the same page, nor within the same lesson, nor even on the same day! It only serves to aggravate the student's confusing the two!