1. From Setup, enter Sharing Settings in the Quick Find box, then select Sharing Settings.
2. In the Account Sharing Rules related list, click Edit next to the rule you want to change.
3. Change the Label and Rule Name if desired.
4. If you selected a rule that's based on owner,skip to the next step. If you selecteda rule that's based on criteria, specify the criteria that recordsmust match to be included in the sharing rule. The fields availabledepend on the object selected, and the value must be a literal numberor string. Click Add Filter Logic... to changethe default AND relationship between each filter.
5. Select a setting for Default Account, Contract and Asset Access.
6. In the remaining fields, selectthe access settings for the records associated with the shared accounts.Access SettingDescriptionPrivate(available for associated contacts,opportunities, and cases only)Users can’t view or updaterecords, unless access is granted outside of this sharing rule.Read OnlyUsers can view, but not update,records.Read/WriteUsers can view and update records.Note Contact Access is not available when the organization-wide default for contacts is set to Controlled by Parent.
7. Click Save.