Welcome Tom. The electrical systems of an old vehicle are the hardest to figure out, so go slow and learn how everything works(is supposed to), before spending too much on new parts.
These have a dimmer switch that directly controls the dash and interior lights, the "wheel" just to the right of the main switch. So that you need to play with to see how it brightens the light. It also turns them completely off or on, pushed all the way down or up(early models didn't have all three functions). That dimmer switch is a weak link, suspect that often with lighting issues.
The optional automatic headlight feature is also a main possible control circuit. If your truck has that, be sure which kind of lights control is being on(is that turned off, or to some level of time delay). That is in the mirror on these Explorers, so sometimes the mirror can create the electrical issue, lights flickering etc.
So I suggest playing with the controls and figure out which are not part of the problem, and which can be. It sounds like a control issue, not bulbs or a simple fuse problem.