Look at the layer in the timeline. You see the switch that looks like a dotted backslash? It needs to be a forwards slash
If you are on a windows machine do this:
- Make sure the magnification ratio of the composition panel is set to 100%
- Make sure Comp Resolution is set to AUTO
- Select the text layer that is giving you problems and press the U key twice to reveal all modified properties
- Make sure that the character panel is active and shows the properties of the text layer
- Make sure your composition is selected in the Project Panel so we can see the settings
- PrintScreen
- Return to the forum and paste (Ctrl + V) to show us your screen shot.
If you are on a Mac create a screenshot by pressing Shift + Ctrl/Cmnd + 3 and drag it to the reply field.
Now we can see what you see and everything should be easy to diagnose and fix. The most likely cause of pixelated text is that the Magnification Ratio is set to something like 800% and you are using a very small font. If this is the case you don't understand the AE UI or how video works and you need to do some studying.
There are other problems with small fonts that can be caused by color values that are way out of spec, white text against a black background or small thin text not properly lined up with the pixel grid but these don't usually show up until you render. There are also problems with moving text when it is small and doesn't move precisely an whole number of pixels every frame.
If you don't know what I'm talking about in the instructions take some time to study and learn the user interface.