Method 2 – Deleting PlayerPref files

I have found that Method 1 doesn't always work for me and sometimes my resolution settings are not reset. If you are unable to get Method 1 to work for you (or you just feel like doing it another way), you can find the PlayerPref files on your computer and delete them manually. To delete the files manually, complete the following steps:

1. Determine Company Name and Product Name from PlayerSettings by navigating to Edit | Preferences | Player Settings:
   
   

2. Now, select (Windows) Start and type regedit. Select the regedit program when it becomes available to you:
   

3. The Registry Editor should now be open. Navigate to the folders that represent the Company Name and Product Name you found in step 1, by the following path:

• Computer
• HKEY_CURRENT_USER
• Software
• The Company Name Found In Step 1 (DefaultCompany)
• The Project Name Found In Step 1 (Mastering Unity UI Project):
  
  

4. Once you select the appropriate folder, you should see the following items on the right-hand side of the Registry Editor:

• Screenmanager Is Fullscreen
• Screenmanager Resolution Height
• Screenmanager Resolution Width
  

5. Select all three of the listed items and delete them:

6. Rebuild the game, and the new resolution settings should now be displaying.