subform

[Alaska1]

I have a main form Contact Details and a subform. I am trying to link the subform to the primary key which is ID but cannot field the option in properties when clicking on the subform. I cannot find Child Link Master. The subform I created is a command button and when you click on it opens up. I am not sure why I cannot find the links field when clicking on properties in the subform. My ID field is set as a primary key.

[isladogs]

Open the main form in design view.
Click on the outline of the subform. This can be tricky if you have A2016
What you are actually doing is clicking on the container that holds the subform and not the subform itself.

In the properties sheet, you should now see master and child entries ready for you to populate.

[Alaska1]

Thank you for quick response. I think my problem is I created a new form and added it to the main form as an command button. I want to be able to click on the text and open up the form and have the data link back to the main form. If I created a subform using the wizard and I am not able to click on the field and have the form come up.

[isladogs]

I think my problem is I created a new form and added it to the main form as an command button.

I assumed this was a typo in the original post.

If its another form within the main form, then it's a subform but you shouldn't use a button click to make it visible

If you mean that your button code opens a completely separate form, then its not a subform.
If you are opening a completely separate form, you can filter it so it opens to the same or a related record

[Alaska1]

Thank you. It is not a subform. It is a form. Is the option to filter on related or same record in properties?

[isladogs]

Look up DoCmd.OpenForm in access help

You will need code something like this

DoCmd.OpenForm "MyNewFormName", , ,"FieldName = 'some value'"

For example,
[

DoCmd.OpenForm "Employees", , ,"LastName = Smith'"

You could also try watching Access videos on You Tube.
For example: https://www.youtube.com/watch?v=RILqSTAAQpM may be helpful