1) Copy our web address by highlighting our URL, right clicking and selecting ‘Copy, or by pressing CTRL and C together.
2) Click on the Firefox menu
3) Select ‘Preferences’
4) Click on ‘Content panel’ and go to ‘Block Pop-up Windows’
5) Once here, select ‘Exceptions’
6)  Paste our web address into the box by right clicking and selecting ‘Paste’ or pressing CTRL and V together.
7) Press ‘Allow’.