How to make modified broad match keywords?

I wonder how exactly do I turn regular broad match keywords into modified broad match ones? I mean, I know the general guidelines like so:

+red +shoes

BUT…I’ve also noticed inside of Adwords interface this:
In “Campaigns”-“Keywords” I can put a checkmark to the left of a certain existing keyword, then I click on that keyword and a small rectangle pop-up window appears in which there’s a box where I can edit my keyword AND A DROP-DOWN menu where I can choose a match type. BUT I can only choose those types:

Broad match
Exact match
Phrase match

There’s no Modified broad match option there!
And if I MANUALLY just add a + in front of a broad match keyword, it remains the same “Broad match” type (when I go to “Keyword details” and choose "Auction insights - single keyword only), then I get a new page and there I see just “Match type” Broad. Is there a place in Adwords interface where it clearly STATES that that particular keyword is a MODIFIED Broad match? Or it’s just silently implied without being mentioned?
And the last thing…what would be the best practice to check which search queries trigger my MBM keywords?
Just give it some time and check the results. The thing is…I do know how to check what was the search query that made my clicked ad show in a first place, but…what I don’t know is how to find out which exact keyword that same search query triggered.

It sounds like you are trying to adapt the queries/searches to keywords, which seems rather odd.
Keyword optimisation is not some sort of magic trick that suddenly draws thousands of visitiors that otherwise would not have come to your site. I suggest you research keywords and their uses; hundreds of books and milllions of online articles about the subject.

There is no separate columns for Broad modifier in the Adwords Interface and simply adding a (+) sign is enough to indicate it as a Broad Modifier. But be sure that you are using the + sign correctly. Don’t leave space between the + sign and the keyword. Then it won’t count as Broad modifier.