Normally CamBam saves the sizes when closing the programme. All you have to do is tick the box under "Tools".
In V1 32bit this also works perfectly for me.
In V1 64bit it does not work for me (Win7 64bit). The document (CamBam1.0.config) is read, but the size settings are not written. Since other settings, such as template path etc. are written, it is not a rights problem.
So I copied the 32bit "CamBam1.0.config" file into the 64bit Program-Data path and it works.
ralf