If your account is connected with multiple companies and you can switch to another by following 2 steps. 

Step 1. Click Switch Company

Step 2. Switch

Click on the company drop-down box on the top right corner , select the company you would like to enter, and you will be redirected to another company's page in three seconds.

Tips:
By default, companies are listed in reverse order of creation time, and the first company added or created is shown at the bottom.
For those companies that is not active, they are not displayed at the multi-company drop-down box.
If you sign out, the company you enter next time is the same company you entered last sign-in.