Add the SharePoint sites to the Local Intranet zone or to the trusted sites zone on the Internet Explorer browser.
Go to Tools > Internet options.
Under Security tab, click Trusted sites > Sites.
Specify the SharePoint site URL and click Add.
Click Close.
IMPORTANT:To enhance the security, enable the following options in the browser:
Go to Tools > Internet Options > Advanced, and then under Security tab, select Empty Temporary Internet files folder when browser is closed.
Go to Tools > Internet Options and under General tab, select Delete Browsing history on exit.