This is not an encoding issue, but an issue with the requested font that isn't working for some reason. This can happen if the font that is requested is corrupted or otherwise can't be accessed, possibly because the font is under control of a third-party font manager and is located in a non standard location. If Firefox isn't able to access the requested font then it falls back to a 'last resort' font that shows all glyphs as a '?' or an 'A'. *[/questions/1292109] Fonts replaced with question marks in boxes *[/questions/1268528] when I type the number 9, the underscore symbol appears (long dash) ---- You can right-click and select "Inspect Element" to open the builtin Inspector with this element selected. *https://developer.mozilla.org/en-US/docs/Tools/Page_Inspector/How_to/Examine_and_edit_HTML You can check in the <b>Rules</b> tab in the right panel in the Inspector what font-family is used for selected text. You can check in the <b>Font</b> tab in the right panel in the Inspector what font is actually used because Firefox might be using a different font than specified by the website. *https://developer.mozilla.org/en-US/docs/Tools/Page_Inspector/How_to/Edit_fonts