"Adjusting" something means making small changes to it to make it better.

Some other good examples of "adjusting" something are:

• You can "adjust the temperature" in a room on the thermostat.
• Comparisons of money between the past and present are often "adjusted for inflation". That means that the older amounts are multiplied by the amount that the value of money has risen by over time. So $400 in 1980 might be equal to $900 today, for example.
• Before you start driving, you're supposed to adjust the mirrors on your car so that you can see behind the car easily.
• You adjust the settings of a machine, a computer program, or an appliance.