Set the default form that appears when you open a database

From https://support.office.com/en-us/article/Set-the-default-form-that-appears-when-you-open-a-database-94961011-392F-4C3B-8DBC-E5D5ADBFF1DF

This procedure assumes that you have already created the form that you want to display.

1. Click the File, and then click Access Options.
2. Click Current Database, and then in the Display Form list, select the form that you want to display when the database starts.
3. Click OK, and then close and reopen the database to display the startup form.

NOTE: 

• To bypass this option and other startup options, hold down the SHIFT key while you start the database. For more information, see the article Bypass startup options when you open a database.
• By attaching macros or VBA code to the startup form's OnOpen or OnLoad event, you can specify more actions that occur every time that the database starts. For more information about how to create macros, see the article Create a macro.