If you are using a desktop browser, you may be able to change the "zoom" setting by using the [control] [+] or [control] [-] or [control] [0] keys on your keyboard -- that is holding down the control key and pressing the plus, minus or zero key to make text bigger, smaller or reset the size. The settings are remembered for each site, independently.
If you are using a mobile browser or the app, there should be a setting for text size somewhere in your device settings.
