I have several text fields that are set to multiple lines and expand to fit. These things work fine. However, after saving the doc and reopening the form the fields are expanding up instead of down, and overlaping other fields. I must have some setting wrong but I don't know what it is. Help, anybody!
It is difficult to say without seeing the form.
When setting objects to expand, you will need a flowed layout.
This example looks at positioned and flowed subforms: http://assure.ly/eSGQMt
This example looks at expanding objects in positioned subforms (wrong) and flowed subforms (correct): http://assure.ly/e2jR0C.
I suspect that your form structure is not correct and that some of the containers are not set to flowed.
Can you post your form? If so upload it to Acrobat.com, publish it and then share the published link here.