Change Plans

Hi,

Does anyone know how I can change plans? I recently bought into the Lightroom CC plan with 1TB storage but now feel I want to change the plan to have Lightroom Classic on my laptop and cc on mobile. I tried to change plans through the Adobe Lightroom site in my account but is states that I need to change in the Apple store as this is where I signed up. I cannot find where I am supposed to do this and would really appreciate the assistance. Thank you, Daniel