Hello, all! First time posting in here. Hope someone is able to help. Can't find an answer anywhere online!

My company uses Salesforce to keep track of leads and opportunities (nothing fancy). On the leads list, and the snapshot at the top of a leads page (with title, company, phone and email), there are only "phone" and "mobile" listed. Since you can't change the name of those fields, we added a custom "Direct Line" field. Problem is, I can't figure out how to get that to be the main display. 

We want to keep the "Phone" line in use as a company line for when we convert to an account. I've seen issues with people having that field populate with the direct or mobile number they had in for the lead for the whole company. 

The only similar question I've seen asked was from 2011 and the suggestion was writing cross-object formulas, which I can't even find in Setup.