These modes let you choose how the text will be handled in relation to the size of the Text element, and each one is useful for different scenarios. The three available modes are:
Fit in one line
Fit in container
Clip to lines
The following table compares how each mode affects different lengths of texts:
Fit in one line
This is the simplest model. It will fit the entire text in one line, ignoring line breaks.
It is useful for one-liners, names of Poll items, percentages, counts, a contest's hashtag on an upper left or a news headline in a lower third.
Keep in mind that a very long text may become unreadable.
Fit to container
In this mode, the text will try to fill the entire Text Element, and it will keep line breaks.
It is useful for texts that need to be read entirely, like paragraphs or posts' descriptions.
Note that as a text gets longer, its font size will shrink to fit entirely in the given element's dimensions, so very long texts can become unreadably small.
This model has one extra setting: Max font size (%). As its name points out, it is the maximum size the text can have, in relation to the Text element height.
You will notice its impact on a very short text, that may only require a single line to show, but has a lot of blank space available. As the text tries to fit the entire element, it may become extremely large. Setting a max font size will prevent this.
Clip to lines
This mode lets you choose how many lines of text to show, hiding out the surplus.
The size of the text is more controlled in this mode since you choose a fixed amount of lines for a given element's height, but long texts may be clipped.
It is useful for places where space and readability are more important than content, such as a lower third showing a ticker with a preview of the audience's comments as the show goes by.