Migrate saved logins
All cached logins are saved on %APPDATA%\Microsoft\SQL Server Management Studio\%Version%\SqlStudio.bin

Each time you run SSMS and save a login, it is added to SqlStudio.bin file. Now i assume your new SSMS has no saved logins, therefore simply replace SqlStudio.bin with the one from old SSMS 

Steps:

Go to: %APPDATA%\Microsoft\SQL Server Management Studio\11.0\SqlStudio.bin , copy that file and then go to %APPDATA%\Microsoft\SQL Server Management Studio\14.0 and replace the existing one.