I know this can be done via #+attr_latex: :placement [] over the figure itself, but is there a variable I can set this parameter to always be [H] rather than its default value ([htbp]?

When writing C code in org mode, things , after pressing Enter or Tab, like...

*(p2+1)='e';

end up w/ preceding commas. I've tried w/ emacs -q and I have the same issue. Is there any short term fix for this?

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UPDATE

I realize now this is a quoting mechanism to prevent confusion inside an org document, and that this should not be removed. Instead is there a good way to font lock these commas so that they are barely visible?

I want to disable the fortification of things like a_b and a^b while letting things like a^{b} and a_{b} get fontified in org mode. Is there a good way to do this?

Specifically, I want := to show up as ≔ in my buffer, and export as such.

If I do...

(add-to-list 'org-entities-user '(":=" "\\coloneq" t "≔" ":=" ":=" "≔"))

I need to add a backslash before the symbol. Is there a way to achieve what I want?