Salesforce: 设置用户默认访问Lightning Mode

Steps to follow in Salesforce Classic

1. Click on Setup.
2. In the Quick Find search box, enter Apps and click it.
3. Locate the App and click Edit.
4. Select an object as the default landing tab on the drop down arrow.
5. Assign it to Profiles.
6. Click Save.

Steps to follow in Lightning Experience

1. Click the gear icon then click Setup.
2. In the Quick Find search box, enter App Manager and click it.
3. Locate the App and click the drop-down arrow on the right.
4. Click Edit.
5. Click Navigation Items.
6. Under the Selected Items section, select the custom tab and move it up to the top of the list by clicking the Move Up arrow.
7. Click Save.

参考链接：https://help.salesforce.com/articleView?id=000333184&type=1&mode=1

To set a Lightning App as the default app when users login: 

If you are using the Standard Profile User Interface:

1. From Setup, enter Profiles in the Quick Find box, then select Profiles
2. Select a profile and scroll to the 'Custom App Settings' section.
3. Select Default next to the Lightning app.
4. Log out and log in again.

但是要注意，该设置只能设置user第一次访问salesforce时的app。如果user登录后更改了自己的app，那么下次登录时，将显示user更改后的app页面。