The following instructions will show you how to make the fonts on your TinyMCE editor a little bigger than the default 10px. If your eyes are not as good mine, then you may need to increase the fonts to something a little bit more legible. Font sizes bigger than 12px would do.
If you are not familiar with TinyMCE, it’s a popular web-based text editor used by many web applications, CMS and blogging software. WordPress uses TinyMCE editor as well, which is the blogging software for this blog. Now, if you need to increase the size of the text in the textarea, then you will need to edit the several themes that came with TinyMCE.
I ended up editing several themes anyway because I didn’t clear the cache at first, and I kept trying different themes without seeing any changes. You will need to clear the cache in your browser to really see the desired results.
There are a total of 4 different themes in the TinyMCE folder. They are located at: tiny_mce/themes/advanced or tiny_mce/themes/simple folders. Change the font size for the textarea of the theme you are using. I found the CSS at the top of each file.
Clear your cache and reboot. You should see a much bigger font size of 12px.