Text confusion

See:

• https://musescore.org/en/handbook/4/staff-text-system-text-and-expressi…

• Text frames is another thing: https://musescore.org/en/handbook/4/using-frames-additional-content#uses

Fermata, caesura, and breath marks are not (strictly speaking) any kind of text.

Staff text is attached to a specific note (occasionally a specific measure) in a specific stave. This would be instructions that apply to only one instrument. For example, the trombone might be instructed to use their mute while other brass instruments do not. Or the flute might be instructed to play espressivo while other instruments are expected to continue playing with some previously notated expression text.

System text is attached to a specific note or measure, but it is applicable to ALL staves. Prime example would be rit. or accel.. It would be very unusual for one instrument to speed or slow while the others stay the same tempo.

A text frame is a box ("frame"!) outside the staves that can hold text and nothing else.

In fact, you missed two of the possibilities: Both vertical and horizontal frames can also hold text. You right-click on the frame border and click to Add / Text. Using a vertical frame like this is how you can place multiple columns of text in the same place. (For example, putting multiple columns of verses to a many-versed song after the notation.) Because the text frame can only have one piece of text.

Experimentation with the different types is the best way to get to know them. And don't worry if you don't know it all. I just learned about using the Vertical Frame to include multiple columns of text a month or two ago and I've been using the program for something like 6-8 years.