BetteTheRed ----your quote -----Point is, reputable scholars/translation experts can parse that one little phrase in Verse 7 in three distinctly different ways, -----
This is my view ------from the Hebrew ---
Read all here ----
http://biblehub.com/lexicon/genesis/4-7.htm
and thou shalt rule
mashal (maw-shal')
to rule -- (have, make to have) dominion, governor, indeed, reign, (bear, cause to, have) rule(-ing, -r), have power.
NASB ©HebrewTransliterationStrong'sDefinitionOrigin
"Ifאִם־im-
518ifa prim. conjunction
you doתֵּיטִיב֙tei·tiv
3190to be good, well, glad, or pleasinga prim. root
well,תֵיטִ֔יבtei·tiv,
3190to be good, well, glad, or pleasinga prim. root
will not [your countenance] be liftedשְׂאֵ֔תse·'et,
7613exaltation, dignity, swelling, uprisingfrom
nasa
up? And ifוְאִם֙ve·'im
518ifa prim. conjunction
you do not do well,
3190to be good, well, glad, or pleasinga prim. root
sinחַטָּ֣אתchat·tat
2403bsin, sin offeringfrom
chata
is crouchingרֹבֵ֑ץro·vetz;
7257stretch oneself out, lie down, lie stretched outa prim. root
at the door;לַפֶּ֖תַחlap·pe·tach
6607opening, doorway, entrancefrom
pathach
and its desireתְּשׁ֣וּקָתֹ֔וte·shu·ka·tov,
8669a longingfrom an unused word
is for you, but
you must masterתִּמְשָׁל־tim·shal-4910to rule, have dominion, reigna prim. root
it."
4910. mashal
►
Strong's Concordance
mashal: to rule, have dominion, reign
Original Word:מָשַׁל
Part of Speech:Verb
Transliteration:mashal
Phonetic Spelling

maw-shal')
Short Definition:rule
NAS Exhaustive Concordance
Word Origin
a prim. root
Definition
to rule, have dominion, reign
NASB Translation
dominion (1), gain control (1), govern (1), had charge (1), have authority (1), master (1), obtain dominion (1), really going to rule (1), rule (27), ruled (5), ruler (18), ruler's (2), rulers (6), rules (9), ruling (3), wielded (1).
and thou shalt rule
mashal (maw-shal')
to rule -- (have, make to have) dominion, governor, indeed, reign, (bear, cause to, have) rule(-ing, -r), have power.
Parallel Verses -----all same the same thing ------all the same meaning ----Strong's 4910 --look it up
New American Standard Bible
"If you do well, will not your countenance be lifted up? And if you do not do well, sin is crouching at the door; and its desire is for you, but
you must master it."
King James Bible
If thou doest well, shalt thou not be accepted? and if thou doest not well, sin lieth at the door. And unto thee
shall behis desire, and thou
shalt rule over him.
Holman Christian Standard Bible
If you do what is right, won't you be accepted? But if you do not do what is right, sin is crouching at the door. Its desire is for you,
but you must rule over it.
"
International Standard Version
If you do what is appropriate, you'll be accepted, won't you? But if you don't do what is appropriate, sin is crouching near your doorway, turning toward you.
Now as for you, will you take dominion over it?"
NET Bible
Is it not true that if you do what is right, you will be fine? But if you do not do what is right, sin is crouching at the door. It desires to dominate you, but
you must subdue it."
I did look up This Book ----It is a Fictional Book -----written by man who in my opinion is putting his own interpretation on these words ---but this is just my view
Nowhere do I see these words below in these scripture -----it says you must rule over it -----you must subdue it ----will you take dominion over it -
and this one which is the second one you posted says -----and thou
shalt rule over him.
Do thou" rule over sin - an instruction
2) "Thou shalt" rule over sin - a predestination
3) "Thou mayest" rule over sin - a choice