'Fixed' in the Bible

My heart is fixed, O God, my heart is fixed: I will sing and give praise.

{A Song or Psalm of David.} O God, my heart is fixed; I will sing and give praise, even with my glory.

He shall not be afraid of evil tidings: his heart is fixed, trusting in the LORD.

And beside all this, between us and you there is a great gulf fixed: so that they which would pass from hence to you cannot; neither can they pass to us, that would come from thence.