I have trouble placing my Images inside my document. Everything compiles fine but the figures have always the placement option [htbp] but I want it to be [H] is there a possibility to set an options in mmd Syntax?
Not without using the XSLT customisation system. That gives you full control over output, but unfortunately that will likely require you to install something that will let you process XSLT files, and there wouldn’t be any kind of automation for that from within Scrivener. It’s definitely the more advanced edge of MMD, but if you want to customise everything from top to bottom, even make up your own output formats, that’s the thing to look in to.
Frankly, it might be easier to just do a string search and replace after compiling.