After I exit the game, all settings are constantly reset, including modes of transport budgets, types of vehicle, etc.

Same here, although it doesn't reset everything to default. It does screw up all the settings. It will remove a vehicle group and set random vehicles on all my lines. The number of vehicles is set to a random number (or the default game number). Also when typing line names, it jumps back a character while typing. Not game-breaking that last one, but annoying.

I have same issue