Text Field Spacing

That shouldn't happen if you've enabled multi-line in that field.

If you have enabled multi-line in conjunction with the Rich-text property option and still get this problem I can think of a few possibilities:

• Make sure that you're not copying rich text formatted in another program (like MS Word, for example) and pasting it onto this field.
• Pasting text from another program into this field will also inherit spacing properties that are not included as a feature in Acrobat for the text field properties when using Rich-Text.
• However, when you open the "Form Field Text Properties" toolbar while editing the text inside of that field, notice the button that is labeled "MORE".
• Clicking on that button   will open up the Text Field Properties dialogue window.
• There are two tabs of interest to work around your issue: "Font" and the "Paragraph" tabs.
• In the Font tab see the blank provided labeled "Baseline Shift"; you may type in a number greater than zero; it is measured in points.
• And in tbe Paragraph tab is where you can handle spacing directly for your paragraphs.

In any case, If you've already tried any of these built-in features without success, I would suggest to delete that textfield and re-create a new one from scratch following the suggestion of  Adobe Community MVP try67.

And worst case scenario, ensure that this PDF was entirely produced with Adobe Acrobat and is not a file conversion to PDF from a different source software. Otherwise, if you think this could be related to a file conversion error, see if the problem gets resolved by recreating the form from scratch.

If, on the other hand, Acrobat was working fine before, and this is happening all of a sudden with every PDF (not just the one you're currently fixing), try clicking on Help --->>> Repair Installation.