I asked a similar question and it was marked as a duplicate of this. After digging, the above answer is unfortunately technically correct. You cannot change the font size of the help documentation through the application.
I found a way to make it usable. Here is my job. In the PyCharm application directory, locate the help directory.
- Make a backup of "pycharmhelp.jar" and name it something like pycharmhelp.jar.bak or whatever. Save this file if you mess!
Using Nautilus, right-click on "pycharmhelp.jar" and open it using the archive manager.
Scroll folders to the "/ pycharm / DefaultCSS /" folder
Copy the "s.CSS" file to your desktop and open it using the editor of your choice.
PyCharm uses two font sizes: 10 pixels for text and 8 pixels for navigation. I decided to double the size, you can customize it to what you like best. Using Find and Replace, I searched for "font-size: 10px" and replaced it with "font-size: 20px" and looked for "font-size: 8px" and replaced it with "font-size: 16px"
After editing the file, save it and close the editor.
Then, in the archive manager, delete the "s.CSS" file by right-clicking on it and select "delete"
Finally, drag a copy from the desktop and drop it into the archive.
You may need to repeat this process several times to get fonts of the size you like. This will not scale the images up, but at least you can read the documentation.
Hope this helps, and if for some reason it didn’t work out, just delete the entire jar file and restore the backup.
-james