The Test case step(Input & Expected Result) the field offered for editing is very limited making the user resize the field manually, and once applied, that new size IS remembered subsequently.
Release : SAAS
Component : AGILE CENTRAL
This behavior difference can be only observed in the test case steps.
The Multi editor field shrinks because of its feature for adding new steps below. When you are trying to add the new Input & Expected Result the field will automatically shrink and the user has to maximize the size.
The field behavior is working as per the design.