While it is possible to be signed into multiple accounts on Office 365, to avoid any confusion, you can open a private / incognito window in your web browser.
When in private browsing mode, no accounts or preferences are saved so you won’t have any problems with multiple accounts clashing.
Google Chrome
1. Open Google Chrome.
2. Open the menu (the three dots in the top right corner) and select New Incognito window.
3. In the Google Chrome address bar at the top of the window, type in www.office.com then click on Sign in.
*The Google Chrome keyboard shortcut to open a New Incognito window is Ctrl, Shift, and the N Key (pressed all at once).
Mozilla Firefox
1. Open Mozilla Firefox.
2. Open the menu (the three lines in the top right corner) and select New Private Window.
3. In the Firefox address bar at the top of the window, type in www.office.com then click on Sign in.
*The Firefox keyboard shortcut to open a New Private Window is Ctrl, Shift, and the P Key (pressed all at once).
Microsoft Edge
1. Open Microsoft Edge.
2. Open the ‘settings and more’ menu (the three dots in the top right corner).
3. Select New InPrivate Window.
4. In the Microsoft Edge address bar at the top of the window, type in www.office.com then click on Sign in.
*The Microsoft Edge keyboard shortcut to open an InPrivate Window is Ctrl, Shift, and the P key (pressed all at once).
Safari
1. Open Safari.
2. Select the File option in the top left corner and select New Private Window.
3. In the Safari address bar at the top of the window, type in www.office.com then click on Sign in..
*The Safari keyboard shortcut to open a New Private window is Control, Option, and the P key (pressed all at once).