Revit question

Hi! I split my wall and went to the properties panel and changed the top offset. However, my wall is not changing and there is no height difference or visible changes in my drawing. How can I fix this?
Thank you!

Select the wall from level one then select ‘detach top base’ in the ribbon and detach it from the floor

where is detach from top base on my screen?

Select the wall in 3d view then you should see it in the ribbon on the right

i detached it and dont see a difference the wall is the same height

Did you set the top offset for the wall? You may need to detach it from the structure and finish

I dont know what these things are. I detached in the top ribbon and my prop panels on my split wall says its set to 40 but its still the same height