Bhagavān means the Almighty God who is the controller of all opulences, power, fame, beauty, knowledge and renunciation. He is the protector of His pure devotees. Although God is equally disposed to everyone, He is especially inclined to His devotees.
(Srimad Bhagavatam----1:1:12----purport).

Synonyms for the supreme source of all energies, as explained in the very beginning of the Śrīmad-Bhāgavatam, are janmādy asya yataḥ (S.B.1:1:1), vadanti tat tattva-vidas tattvaṁ yaj jñānam advayam/ brahmeti paramātmeti bhagavān iti śabdyate, called Parambrahma, Paramātmā or Bhagavān. The word iti used here in this verse completes the synonyms and thus indicates Bhagavān. This will be further explained in the later verses, but this Bhagavān ultimately means Lord Kṛṣṇa because the Śrīmad-Bhāgavatam has already accepted the Supreme Personality of Godhead as Kṛṣṇa. Kṛṣṇas tu bhagavān svayam (S.B.1:3:38). The original source of all energies, or the summum bonum, is the Absolute Truth, which is called Parambrahma, etc., and Bhagavān is the last word of the Absolute Truth. But even with the synonyms for Bhagavān, such as Nārāyaṇa, Viṣṇu and Puruṣa, the last word is Kṛṣṇa, as confirmed in the Bhagavad-gītā: ahaṁ sarvasya prabhavo mattaḥ samaṁ pravartate (B.G.10:8), etc. Besides that, the Śrīmad-Bhāgavatam is the representation of Lord Kṛṣṇa as a sound incarnation of the Lord.
(Srimad Bhagavatam----2:10:7----purport).

Nārada has no other business than thinking of Kṛṣṇa, talking of Kṛṣṇa and preaching about Kṛṣṇa; therefore he is sometimes called bhagavān. Bhagavān means "one who possesses all opulences." When a person possesses Bhagavān within his heart, he is also sometimes called bhagavān.
(Srimad Bhagavatam----4:31:8----purport).

We find the word bhagavān used twice in this verse. Both King Indra and Ṛṣabhadeva, the incarnation of the Supreme Lord, are described as bhagavān. Sometimes Nārada and Lord Brahmā are also addressed as bhagavān. The word bhagavān means that one is a very opulent and powerful person like Lord Brahmā, Lord Śiva, Nārada or Indra. They are all addressed as bhagavān due to their extraordinary opulence.
(Srimad Bhagavatam----5:4:3----purport).