How to find a customer quickly from a long list of custom field called customer (drop down menu)


Hi All,
We want to use a drop down custom field called “Customer Name”. But finding the correct customer name in a long list of custom field is not possible. We need to scroll down to find the correct name.

We can see the possible list of tags when we start writing the tag we want. But the same is not possible in a custom field because we can not search or write in a drop down custom field. Is there an easy way to this?
Best regards,