I think the easiest way to enlarge all websites at once is to use one of these add-ons to set a new "default" zoom level. So normally sites start at 100%, but you can enlarge them 25% by setting the default to 125%.

• Default FullZoom Level
• Zoom Page (includes "fit to window" feature)
• NoSquint

After setting your global or default zoom level, you can still fine-tune the zoom on individual sites using Firefox's standard zoom feature. Either:

• On the graphical application menu (accessed using the button with 3 horizontal bars), the + and - buttons
• Hold down the Ctrl key and use + and - on the keyboard
• Hold down the Ctrl key and scroll the mouse wheel (slowly!)

Does that help?

By the way, you should update Firefox. Because you're running Windows Vista, you got Firefox 43 instead of the current release. Long story. To update, you can use the Help menu, designated by the "?" button. This article has more information: Update Firefox to the latest release.

Try to set layout.css.devPixelsPerPx to 1.0 (default is -1) on the about:config page. You can adjust its value in 0.1 or 0.05 steps (1.1 or 0.9) until icons or text looks right.

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

Thank you everyone for your suggestions with this. I had a feeling that this was simple and it was. I was able to accomplish what I wanted using the + and - symbols in the graphical applications menu. Thank you again and God bless.