Your lookup field will come from the "Parent" in the relationship. In the relationship display, you can find which parent element contributes to the lookup field in the child.
Click on the table's tab, then click "Settings" at the top left. In the page that follows, you'll find a link to the table's relationships.
If, so, just right click on the field name in question.
Select "Edit the field properties for this field..."
Then you can change the title to the field.
This is the answer to your more immediate questions,
There is a lookup field that I need to change the names on.Once you get more comfortable you can start diving into more relationship.
Record PickerThe record picker is used when selecting records from a list. Choose the fields to display in the record picker for this table.
Record picker displays values from:
Column 1: Record ID#
Column 2: Category
Preview record picker
When I click on Preview record picker, I can see the two values, just dont know how to modify them