I used the second answer (by Christian Lindig) to this question to make my own fillable PDF form. I edited it slightly to suit my needs. I tried to make a MWE:
\documentclass[11pt]{article}
\usepackage[margin=2cm]{geometry}
\usepackage[pdftex]{hyperref}
\usepackage{xcolor}
\def\LayoutTextField#1#2{#2} % override default in hyperref
\begin{document}
\newlength\somewidth
\somewidth=.25\textwidth\advance\somewidth-2cm
\def\lbl#1{\hbox to 2cm{#1\hfill\strut}}
\def\labelline#1#2{\lbl{#1}\vbox{\hbox{\TextField[name=#1,width=#2,bordercolor=white]{\null}}\kern2pt\hrule}}
\def\q#1{\hbox to \hsize{\labelline{#1}{\somewidth}}\vskip1.4ex}
\begin{Form}
\q{Question 1}
\q{Question 2}
\q{Etc}
\end{Form}
\noindent I want to write some text first. \begin{Form} \q{question} \end{Form} some more text \begin{Form} \q{question2} \end{Form}
\end{document}
When I do this throughout my document normally I play with the size of the forms (the '\somewidth' and 3cm in this case). I know it is cumbersome but I don't have to do it often and it works with my lack of understanding.
I want to have two form fields in a single line that already has text in it. I have noticed that the environment 'Form' always ends the line after itself, which is problematic if I want to put text or another form next to it. In the example, 'some more text' would be in the same line after the form called 'question' and then the form 'question2' would come behind that as well (ignoring the fact that in this case, it might not all fit in one line). So, how do I prevent this environment from ending the line, or should I solve this in another way?

You must put your fields inside a Form environment (only one per file).. So use only one. You can start and end it together with begin/end document. I have no idea why you choose the one answer and what layout you want. – Ulrike Fischer Jun 11 '19 at 13:18