Before I answer your question, be aware that since Base Camp and Club Central are not integrated, you can “give” your L1 accomplishment to any club you choose. That club’s officers do not have to be the ones who approve it in Base Camp.
With that being said, to change your assigned club in Pathways, after you log into toastmasters.org, click on the Pathways menu in the banner and select Go to Base Camp:
Once in Base Camp, change to the club you wish to assign from the drop down menu:
Then click Log in as a Member. This changes your default club as you access Pathways.