I'm not able to do both options, please add screen shots. Can it be because I'm on Odoo Online?

1. Log in to your Odoo instance as an administrator.

2. Go to the "Settings" module and select "Users & Companies" from the menu.

3. Click on "Groups" and create a new group or choose an existing group to control app visibility for certain companies.

4. Open the group you selected and click on the "Access Rights" tab.

5. In the "Applications" section, deselect the apps that you want to hide for the particular companies. Save the changes.

6. Now, go to the "Companies" menu in the "Users & Companies" section.

7. Select the company for which you want to restrict app visibility.

8. In the company form view, click on the "Access Rights" tab.

9. Locate the "Groups" section and assign the group you modified earlier to the company.

10. Save the changes.

By following these steps, the apps deselected in the group's access rights will be hidden for the selected company. Repeat the process for other companies as needed.

Please note that this method relies on group settings and ACLs, so it may require careful planning and configuration to ensure the desired app visibility for each company in your multi-company setup.

To hide or prevent access to entire apps from individual companies in a multi-company environment in Odoo, you can follow these steps:

1. Enable the "Technical Features" for your user: Make sure your user account has the "Technical Features" enabled. You can check this by going to "Settings" -> "Users & Companies" -> "Users" and edit your user account to enable the "Technical Features" checkbox.
2. Access App Settings: Go to "Settings" -> "Users & Companies" -> "Companies".
3. Edit Company Configuration: Select the company for which you want to hide the app (in this case, Company B), and click on the "Edit" button.
4. Manage Applications: Scroll down to the "Installed Applications" section. Here you can see all the installed apps for the company.
5. Hide the App: Locate the app (App X) that you want to hide from Company B and uncheck the checkbox next to it.
6. Save the Configuration: Click on the "Save" button to apply the changes.