Activate Workbook, when workbook name is changing.

I There,

I have a excel workbook(Workbook1)(XLSM) and it working good for making pdf files. Made search box where i can search for people there name etc from an sheet and create pdf files.
I have made this by using a form, the problem is most of the time i have to open another(workbook2) excel files. Then that(workbook2) file comes active, when i want to use Workbook1(form) again i got an error because workbook1 is not active anymore.

I know when i selected workbook1 each time before using the form it works, but this is not handy.

When i add the code: Workbooks("Workbook1.xlsm).Activate in the form is solves the problem, but the problem is each time if i have made an update the name will change for example to
Workbook1.1.xlsm.

Does any know a way to fix this?

So hopefully somebody can help me out.

Already thanks.

Wilco,