Let’s have a quick little grammar lesson, shall we?
There are inherent differences between using a term as an adjective and an adverb. And many compound-word phrases are handled differently when used as adjectives than when used as adverbs.
So, let’s assume you already know what an adverb and an adjective are. (If you don’t, go to jail. Go directly to jail. Do not pass “Go.” Do not collect $200.)
Given this basic understanding of parts of speech, let me use visual aids to drum this one into the heads of you writers, who should know better. I could have posted dozens of examples, but I assume these few will get the idea across:
So, we say “YES!” to this:

… and “YES!” to this:

… and “YES!” to this:

… and even “YES!” to this:

… and, of course, if you are following along at home, you’ll say “YES!” to this too:

BUT … you would never, never, never say “yes!” to the abomination below—put on this earth by Ikea, an otherwise reputable company that should know better. (Or is Swedish their first language, even in print ads in America?)
So, say “NO!” to this:

Oh, the humanity! May it never be! Woe is I! (Note: “Woe is me” just annoys me.)
And definitely say a hearty, loud “NO!” to this:

I think I’ve made my point. But in case that wasn’t clear …
In simple English (for those of you not easily taught by word-pictures): When using the compound word-phrase “every day,” context is key. If you are placing the phrase in front of a noun, as an adjective to describe that noun, make it ONE WORD. No space. No hyphen. Just one word. (See above gazillion examples.)
If you are using the phrase as an adverb (as in the last two examples), then keep it as the two words it yearns to be.
This very general rule holds true for many multiple-word descriptive phrases acting as a single term. Usually the words are joined somehow (with the trend moving toward eliminating hyphens when possible, especially in terms with prefixes such as “pre,” “non,” “post,” etc.) when used as adjectives before nouns. But when they are used as adverbs, they are often simply two separate words, without even a hyphen.
Of course, in English there are always exceptions, if only to keep proofreaders in business, so always check with the latest dictionary or style guide for the most proper way to use a given term. Be a responsible writer. You won’t see a good carpenter using an ax handle to hammer in a nail, so don’t misuse your tools of the trade. Be proud of how you use your words.
And be open to learning a little bit every day.