You need more information (or multiple fields) included in your connection field drop-down.
Add a Text Formula Field to Your Object
From the data section of your builder, select the object where you want to display multiple fields in your drop-down. Add a new text formula field, we’ll call ours Product Name.
Once you’ve named your new text formula, select each field you want to include, adding symbols or characters between them as desired. In this Purchase Order example, we’ll add Part No - Manufacturer - Description, then click "Add Field" to save it.
Set Display Field to Show Contents of the Text Formula
Select the object in which you created your text formula field. Then click on the Settings tab:
In the Settings tab, you’ll see a drop-down titled "Display Field." Click here and select the name of the text formula field you just created (in our example, this field is called “Product Name”):
Click "Update Settings" and open your app to test the new drop-down. It should display the text formula you created -- a combination of the fields you added. In our example, Part No - Manufacturer - Description are displayed:
You may need to allow your records to update, as this text formula field works like an equation, and will need to query your data to update records based on the new formula.