The prices can also be managed from the Availability and Rate Calendar that you can find in the menu bar:

In the Calendar, you can handle prices more flexible way for all rates, availability, restrictions and strategies.

To change price select one day in a room type (or multiple days) and put the price value:

If you change prices or availability in the calendar and save the changes, the color of the numbers will change to red. This color in the calendar always indicates that manual changes were made there.

If you want to change the price, availability or restrictions for a longer period you can use Bulk Update option. 

See more: 

How to use Bulk Update option?