What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
I am not sure if I have understood your question correctly. You should be able to add an umlaut directly in the form title. Do you mean to say that you are unable to edit the form title?
I did test this and I was able to add the umlaut in the form title. Please be noted that if you are using your form's direct URL, you will have to add the title in the "Page Title" of your form's preferences. Please check the screenshot below:
Hope this helps.
Do get back to us if you mean to ask something else.