If anyone wants to know how to enable the "back" and "forward" buttons in the left upper corner, here's a short explanation:
1. Open the Inseminator.html with a text editor of your choice. I used Visual Studio Code, but I tested this with Notepad++ and Windows Notepad too.
2. press strg + F to search the document and enter "disableHistory". This will give you exactly two results (for ver. 3.1 at least).
3. Go to the second one where the code reads "run disableHistory()" and replace "disableHistory()" with "enableHistory()".
4. And Voila, after a reload of the page you have your beloved back and forward buttons again! By the way, if I read the code correctly, you can go back up to 40 times.
Hope this helps anyone that is annoyed by grinding as me!