how to fix when your phone does not set ringtones to different contacts?

If you have multiple contacts with the same ringtone, you can make adjustments to make them different. In the Phone app, tap Contacts > Edit > Ringtone. If you'd like to assign a custom ringtone to a given contact, tap a contact, then tap Ringtone. Next, select a ringtone, then tap Save.
In order to set different ringtones to different contacts, you need to go to Settings > Sounds > Ringtones, and here you will find several options for ringtones, assign ringtones to specific contacts, etc.

Go to Settings > Sounds > Ringtones & notifications. Click on Notification sound. The ringtone you choose for each contact should be the same. If they aren't, go into Sound settings for the individual contact and edit the notification sound.
1. Go to: Settings - General - Profiles; 2. Select the profile that corresponds to the one you want to edit; 3. Scroll down to the Ringtones section; 4. At the bottom, you'll see a section called Default Ringtone; 5. Tap the Edit button; 6.
In order to set ringtones to different contacts you need to do the following steps:

1. Go to your phone settings, and select the "Sounds" option.

2. Click on the "Ringtone" option.

3. Click the "Sounds" option.

4. Click the "Set a New Ringtone" option.
To change a ringtone on your Android phone:

1. Open your device's Settings menu.

2. Tap Sound.

3. Tap Phone ringtone.

4. Tap a ringtone.

5. Tap OK.