in acrobat pro DC i am not able to have my form automaticly resize the font. I have the text field properties appearance tab set to font size set to AUTO text color black and font to Times Roman

This may not work for everyone but I stumbled upon a solution for me. I was dealing with the same issue and was saving to my desktop. Later I changed this and saved to an external hard drive and for some reason the font began autosizing correctly. The only thing I can think that happened was that saving it to the desktop made it adopt the settings of Preview (I'm using Mac but assume it's the same with whatever is defaulted as the PDF viewer for Windows). I hope this makes sense but that is the only solution I have found.

Hi! I am having the same problem and am also "going mad." I edit the properties of my form fields to auto size font and disable scrolling. I save the PDF, open it back up in Acrobat, and the fields have reverted to their old settings. I've tried creating new fields with the correct default settings, I've tried disabling rich text, I've tried uninstalling and reinstalling Acrobat. Has anyone found a solution?

I was going mad dealing with this problem. I followed the suggestion to create a new text field, which would work until I customised.

The workaround I have found is to uncheck Allow Rich Text Formatting [Properties/Options tab/check box list]. This is obviously not ideal, but I chose auto-resize and plain text over scrolling and rich text. Hope this helps someone else! 

I am also having this issue. Auto font size is set, but once I reach the end of the box I can't enter any more text.

Adobe Acrobat Pro DC -- SAME PROBLEM. No matter how I set this form field, the text will not auto reduce to fit.

Font is set to Auto

Multi-line turned off: user can only type 1 line of type

Multi-line turned on: they can type all they want, but it ends at the end of the field

Scroll long text on: a scroll bar is added, so not all the text shows up when the completed form is printed

Scroll long text off: they can type all they want, but it ends at the end of the field (same as "Multi-line on" above)

Is the Acrobat Pro DC causing the problem or is it Reader DC misinterpreting the field?

The Auto option doesn't change the size of the field, but the size of the text in the field.