Text that is too small strains the eyes, and text that is too large can cut off buttons. Your phone lets you adjust the size without changing the rest of the screen.

Android

1. Open Settings, then Display.
2. Tap Font size and style or Font size.
3. Move the slider to a size you can read comfortably, and check the preview text.

On some phones, Display size is a separate setting. It changes how big buttons and icons are, not only the text.

iPhone

1. Open Settings, then Display & Brightness.
2. Tap Text Size and move the slider. For larger text across apps, open Accessibility, then Display & Text Size, then Larger Text.

If apps look wrong

Some apps have their own text size inside their settings. Very large text can push buttons off the screen, so go back one step if a screen stops making sense.