Settings - Expansion
This second part of the Settings tab allows you to set various options that affect expansion.

Disable keyboard expansion should be quite self-explanatory: if you check it, TypeIt4Me will no longer expand your abbreviations automatically as you type.
Don't append trigger: check this one if you don't want the character that triggered the expansion to be appended at the end of the expanded clipping.
Case sensitive expansion: if you check this option, you will have to type the abbreviation in exactly the same case as it was defined in or it won't be expanded. However, TypeIt4Me will not allow you to define two identical abbreviations, even if you type them in a different case. So, if "abb" exists, you cannot also define "Abb" or "ABB".
Don't match Abb Case: this turns off the feature whereby the entry is typed starting with a Capital letter or in ALL CAPS if you type the abbreviation starting with a Capital letter or in ALL CAPS.
Strip 's' for plurals: this allows you to define abbreviations only once for both singular and plural. Suppose you define abb = abbreviation: without this option, you would also have to define abbs = abbreviations or you would have to type abb, a space to trigger the expansion to abbreviation, then a backspace and finally type an s at the end of abbreviation. Instead, if you choose to strip 's' for plurals, you'll be able to type abbs and see it expand to abbreviations, without the need to define abbs. By default, this feature is off since it can have some unexpected results for users who have already defined lots of abbreviations using previous versions of TypeIt4Me.
Play sound on expansion:
Select this if you wish to hear a short blip every time you trigger an abbreviation.
Don't restore Clipboard:
Select this only if TypeIt4Me consistently expands the contents of the clipboard instead of the clipping corresponding to the abbreviation you typed. This may occur on slower Macs or when many applications are open and event handling slows down.
The up side is you will always get the right clipping expansion, the down side is you will lose whatever was copied to the clipboard before the abbreviation was triggered.