I presume when you say your basement is at a "lower height than the other floors" you mean that the walls are a lower height. If that is what you meant, then you need to elevate the floor level of the basement and the walls will move up accordingly.
All elevations are calculated from Terrain (or ground) Level, which is regarded as zero. As in the image, the Foundation floor level is MINUS 2440mm (-8') and since the walls are the same height, everything joins up. If you have reduced your walls to 2140mm (7') for example, then you must also change the Foundation Floor Level to -2140mm (-7'), so it brings the floor of the Foundation closer to ground level and the walls with it.
Incidentally, if you change the Location setting of the Wall Height, it will not automatically change any existing walls - only new walls, entered after you change the setting, will assume the correct height. If you have 2440 (8' walls) sitting on the Foundation level and change the Foundation to 2140 (7') your existing walls will move up accordingly and push through the floor above. You must change pre-existing walls manually or replace them with new walls that are set to automatic so they will assume the new height setting for that Location.
Hope that all makes sense!