Don't select any option. Especially "Always match route to the map" can cause broken routing (straight lines) when selected.
Basecamp has replaced Mapsource as Garmin's default mapbrowser and has some nice features like 3D (not available on Openfietsmap, choose in Map Views 2D map - Ctrl+2), better track management, filtering road or waypoint types and better elevation profiles. However, routing is only compatible with the latest GPS devices (Etrex 10/20/30, Montana, GPSmap62/64, Oregon x50, 6x0).Device transfer
Garmin does not update Mapsource anymore but the software can still be used and is recommended for older pc's in combination with older gps devices.
In the menu Edit>Options (Ctr+O) > Activity Profile
Driving will avoid semi/unpaved trails, in the activities Bicycling/Tour cycling Toll road avoidance (will route on bike routes, see below) is unfortunately not available in this profile. Activity type Walking will ignore oneway streets which can be useful in cities. Hiking will do the same but here are Interstates/Major highways selected and greyed out (interstates/major highways are cycleways and -routes on OFM)
Some recommended profile settings