The best solution is to reset the parts of your site that are bugged. You can follow our guide on resetting templates here: How to Restore a Template Page Back to Default.
If the issue is that the text size is too large, you can use the Superb Addons plugin to create two separate headlines—one for mobile and one for desktop. Then, use the “Hide on mobile” and “Hide on desktop” features in the plugin to ensure each headline displays properly on the respective device.