Moonmania64 if you press the little tower icon after the buy max button, than it will lock in the maximum that you need to lvl up the building. If a building needs 100, you have 10, and the tower is pressed in than it only lets you buy 90 and after that 90 is bought it turns the buy max into 0.
You can restart by opening the "Company" tab, scroll to the buttom and click the "Restart Company" button, then confirm that you really want to restart.
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You can restart by opening the "Company" tab, scroll to the buttom and click the "Restart Company" button, then confirm that you really want to restart.