Currently the the Lightning Experience UI only allows to display 4 fields on a related list. You would need to click "View All" to see all fields. This is a regressed functionality, given the fact that the same layout in classic version is capable of displaying 10 fields in related section. A busy user in the servicing world could benefit by being able to see all information on screen, so as to be able to get info at a glance, or do a Cntrl+F on the layout. Rather than having to click through each related information section to get full context. Requesting Salesforce to bring the number of fields rendered on Lightning Experience related information section to be on par with what is available in Classic view.