From the Pricebook menu, choose Pricebook Management and the Manage Pricebook
Once inside the Pricebook do a search for what you are seeking. Move to the right of the item you would like to change and then click the price and give a new one. Once done with your price changes go to the Save button and a new box will pop up. This is asking you if you would like to save and update the POS, make sure to select update only CHANGED items to POS and then select OK.
Once OK is hit, a Price Update Confirm page will pop up and you can see your price change you made listed. Go towards the bottom of the page and select Update Changed Price(s) to POS, and it will process through.
If you need to change prices on a batch of items at one time, hold the CNTRL key on your keyboard to select multiple items.
Then right click to change price
Click OK and then click the SAVE button at the top of the page to send items to POS.