Step 1

• Select Gear Icon (top right)
• Select Setup
• Type “Sharing Settings” in a Quick Find box
• Select Sharing Settings
• Click “Edit” Button 
• Choose “Private” from the list in Default Internal Access column (this will make all user to see their own data globally)
• Click Save

Step 2 (Optional)

    Set specific user with Permission to see the data of other user when all Objects are set to private:

• Scroll down to Sharing Rules section
• You would need to assign permission to a user for each Object
• Find the Object you need
• Click on New button
• Enter the Lebel Name in a Rule Name (Step 1) section
• In “Step 3: Select which records to be shared” section choose the Roles for “(Object Name) owned by members of” and select the User
• In “Step 4: Select the users to share with” section choose Roles for “Share with” and select the User
• Choose Access Level in “Step 5: Select the level of access for the users”.
• Click Save.

Step 3

• Type “Profiles” in Quick Find box
• Select “AscendixRE Standard User” profile
• Click the “Edit” button
• Scroll Down to Standard Object Permissions and Custom Object Permissions sections and make sure the “View All” option is unchecked for all Objects.
• Click Save