Access - Multiple people in database

Hi Steph, Welcome to the forum, thank you for your post, in answer:

Access is opened as a multi user program, to do what you ask it is necessary to open the program in this manner;

Open Access program,
Click File>Open, Navigate to your chosen database and select it (single click) in the Open File dialog box, at the bottom corner is the Open button, the Open button has a drop down option, in the drop down option select Open Exclusive.

You now have the database open exclusivly, this is a temporary solution and will only be in force as long as the database is open.

As I said at the beginning, Access is by default a multi-user progam, still I hope that has helped, if so please click the resolved link, regards Pete