Facebook lets you decide who sees what you post on your wall. It does this through privacy preferences. If you go to the menu with the three horizontal lines, you will find the Privacy shortcuts button.

Among the various options is Review a few important privacy settings. Tap on it to see more privacy settings.

Since the goal is to control who sees what you share, tap on Who can see what your share.

Tap Continue to start the privacy wizard.

First, you have choices regarding your personal information. Adjust these parameters if necessary. To continue, tap on Next:

In the Future posts section, tap on Friends, this is the default option.

Select who will be able to view your posts from now on.

Repeat the process with Facebook stories tapping on Stories. Similarly, if you want to apply the same restrictions to your previous posts, tap on Limit.

Confirm this last change by tapping on Limit again.

The final step of the wizard will let you block some users. To finish, tap on Next.

With this method, you will have modified the default settings of everything you share. However, you have privacy control in the post editor.

If you change this setting, the setting will only apply to that particular post. The default settings will remain the ones you chose in the privacy wizard.