God is sovereign over everything and everybody all the time. Period. (See Chapters 2-5 in When Storms Come: Will You Be Ready?)
Does that mean God is sovereign over our sins?
God is sovereign over our sins, but we are entirely responsible for them.
God does not cause evil, He is not tempted by evil, nor does He tempt anyone (James 1:13). We are responsible for our own behavior.
God can prevent our sins (Genesis 20:6), but, clearly, He often does not.
When we sin, as children of God we are responsible to confess our sins. Our faithful and righteous God then forgives us our sins and cleanses us from all unrighteousness (1 John 1:9).
Even though we are forgiven if we confess, most likely there are consequences from our sins.
The good news out of this bad news is that God, in His providence, uses our sins for His purposes. (For example, Proverbs 19:21; Lamentations 3:37.)
Since He is sovereign, eternal, and omniscient, He not only knows what “will” happen, but whatever happened—whatever He allowed—was/is part of His plan. He works all things in accordance with His will.
This explains the familiar promise: God causes all things to work together for good to those who love God, to those who are called according to His purpose (Romans 8:28).
So…what bad thing just happened to you? God knew about it from before the foundation of the world (He is eternal). He allowed it (He is sovereign). If you’re a believer, He will use it for good.
If you’ve sinned, confess it, and seek to walk in His way.
But whatever the circumstance: