Within Teamwork.com, you can reset a user's password by resending their invitation to your site.
Click the More option from the main navigation and select People from the dropdown menu.
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In the people area, select the People tab from the horizontal menu.
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In the top right of the People list, click the options button (three dots) and select Send Invites from the dropdown menu.
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In the Send Invites modal, go to the Resend Invites tab where you can choose from the list or search for the user's name. You can also filter to a specific company's users.
Check the box to the left the user's name and click Send Invite Email Now.
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Once the invite has been sent, the user will receive a link where they can set/reset the password they wish to use for accessing their your Teamwork.com site.
Note: By default all users are required to create a strong password. This must consist of at least 8 characters in length and include one letter and two numbers.
For more information, see: Changing Your Password