If you truly need tex to throw all layout reasoning out the window and place the figure where you include it in the source you need to use H (may require the float or floatsomething package).
h - somewhere here please
t - allow this figure to be placed as the first thing on a page
b - allow this figure to be placed as the last thing on a page
p - allow this figure to be placed on a page with no text at all
\begin{figure}[htb!] ... \end{figure}Picture still appears below appendices instead of introduction
Shouldn’t it be only h! if you want the picture to appear where you place it?
If you truly need tex to throw all layout reasoning out the window and place the figure where you include it in the source you need to use
H(may require the float or floatsomething package).h - somewhere here please
t - allow this figure to be placed as the first thing on a page
b - allow this figure to be placed as the last thing on a page
p - allow this figure to be placed on a page with no text at all