It sounds like you need to create a flowed document with text fields that have specific field properties so your text fields expand (aka fit all the extra text users enter).
Your entire document, notably the part containing this page icon:
...needs to be selected and on the Object > Subform panel the following options should be what's below:
For your content -
For content that won't expand to fit more text, all elements must be placed within a subform.
Check your hierarchy and make sure anything you've laid out is nested in a Subform (you'll find these in your Object Library) that's set to 'Postioned', visual below:
The text fields will need to be outside the subforms in the hierarchy.
They also need to have these options in their Object > Field panels:
ALSO, under your text fields' Layout panel under 'Height' select 'Expand to fit' (very important**)
Let me know if this helps!