How to make text bigger in a text editor
In Jotter by Zaweba, hold Ctrl and roll the mouse wheel, or press Ctrl+Plus and Ctrl+Minus, to zoom text from 50% to 400%. Ctrl+0 sets it back.

Hold Ctrl and roll the mouse wheel forward. In Jotter by Zaweba that zooms the text, anywhere from 50% to 400%. Ctrl+Plus and Ctrl+Minus do the same from the keyboard, and Ctrl+0 puts the text back to 100%. The current zoom is shown in the status bar, so you always know where you are.
It changes only how the text looks on your screen, not the file, so you can make it as big as you like without affecting anything you save.
The three ways in
The mouse wheel is the quickest for most people: Ctrl and roll forward to enlarge, roll back to shrink. On a laptop without a wheel, the keyboard shortcuts are easier. Ctrl+Plus zooms in a step, Ctrl+Minus zooms out a step and Ctrl+0 resets.
The View menu has the same commands, named Zoom in, Zoom out and Reset zoom. They are useful if you forget the keys, or if you are showing someone else how to do it.
When bigger text helps
Reading from further away is the obvious case. A list on a laptop on the kitchen counter, notes on a screen in a meeting room, or a set of instructions you are following while working on something else all benefit from large text.
Comfort matters too. Long sessions with small text are tiring, and a modest zoom can make a real difference over a working day. Some people simply see better with larger text, and zooming is quicker than changing settings for the whole of Windows.
Going the other way is useful sometimes. Zoom out to 50% and you see much more of a file at once, which helps when you are hunting through a long log or getting a sense of how a file is laid out.
What to expect from the layout
With word wrap on, larger text folds into more, shorter lines, so you scroll down more but never sideways. With word wrap off, long lines reach the edge of the window sooner and the horizontal scroll bar comes into play. For reading notes and prose at a large size, turning word wrap on in the View menu gives the most comfortable result.
The status bar also shows the line and column you are on, so even with very large text you can keep track of where you are in a file.
Why it doesn't change the file
Jotter is a plain text notepad. A plain text file has no font size in it at all, just characters. Zoom is a viewing setting, like stepping closer to a page. So a configuration file, a script or a list of figures is saved exactly as it would have been at normal size. If you want a document with real font sizes and formatting, Write by Zaweba is the app for that.
If the text changes size by accident
It is easy to zoom without meaning to, by touching Ctrl while scrolling. If the text suddenly jumps in size, look at the zoom figure in the status bar, then press Ctrl+0. Everything goes back to normal in Jotter by Zaweba with that one key.