As the first ultra high frequency (UHF) station in San Diego, it struggled to attract viewers and advertisers; at one point, it cut back its schedule to two hours a night, and when it was sold to Bass Brothers Enterprises in 1967, it went off the air for nearly six months, returning as KCST with an emphasis on local sports coverage.

In 1976, after finding itself suddenly in first place in the national ratings, ABC sought an upgrade and agreed to move its programming to KGTV; channel 39 affiliated with NBC instead.

[9] It was an independent station, San Diego's first, with a 12-hour broadcast day featuring color movies in prime time,[10] shows for children (Suzy Mallery's Kaartoon-O-Rama) and teenagers (Kaar A Go Go),[11] This format was not a success.

In August 1966, citing a lack of advertising, KAAR cut its broadcast day to 7 to 9 p.m. from Monday to Saturday, carrying the same movie every night in the first week of its curtailed operation.

[15] KAAR restored much of its lost broadcast day after the shift, instituting a late-afternoon children's block, a nightly talk show covering local issues, and a 9:30 p.m.

[22] That March, channel 39 signed a deal to become the official station of the San Diego Chargers football team, airing live preseason road games, a weekly coaches' show, and highlight packages.

When the Chargers drafted cornerback Jim Hill that year, he was assigned number 39 on account of the KCST pact; he hosted a variety show, Mr. 39 Talent Time, and conducted interviews.

[24][25] Between February 1968 and March 1969, KCST grew from having just eight to ten employees to a staff of 45, and Bass's broadcasting division moved its corporate office from Texas to San Diego.

KCST argued that it was the third station, it would do a better job than XETV at providing local programming, and it was available to become the ABC affiliate, rendering the reason for the original grants moot.

In the petition, Western Telecasters revealed that it had lost $650,000 running KCST between February and November 1968 in spite of a $1.36 million expenditure on improvements to the station.

[31] ABC had argued, for its part, that it was already losing money and could not afford an additional $1 million in annual projected losses from a forced affiliation switch.

The commission agreed with KCST's contention that the initial rationale for the annual authorization no longer existed with a third commercial TV station in San Diego itself and found that "as an ABC affiliate, KCST's programming would meet the needs and interests of the community more effectively than the existing ABC affiliate", XETV, which had "not produced a local news program since 1967, does not contemplate resumption of one, and has never interrupted its broadcast schedule for a bulletin of local interest".

[29] ABC and XETV then signed a memorandum of understanding and proposed to the FCC that the network continue with the Tijuana station until July 1, subject to negotiating an affiliation agreement with KCST.

[49] Though the sale of KCST to Storer was announced in March 1973 and a contract formally signed that June,[50] the local chapter of the National Organization for Women (NOW) petitioned the FCC to deny the transaction.

The increase was so significant that it propelled KCST-TV to first place in prime time, beating KFMB-TV and KGTV in share in the February 1976 Arbitron sweeps period.

Lead anchors Dennis Morgino and Laura Buxton remained a team from 1981 through 1987; Mark Sauer of The San Diego Union called their tenure "remarkable" given the circumstances.

[77] KKR had purchased Wometco Enterprises the previous year, after no succession plan was found following the death of chairman Mitchell Wolfson,[78][79] and began the process of dismantling the conglomerate.

[88] In 1987, George N. Gillett Jr. acquired majority control of the Storer stations;[89][90] the $1.3 billion deal was financed through junk bonds[91] and represented a valuation of nearly 15 times cash flow for the group.

It paired Allison Ross, a former KFMB-TV anchor, with Roger Hedgecock, a former San Diego mayor then hosting a talk show on KSDO radio.

[110] The program was canceled after 15 months due to low ratings, particularly as the popular The Oprah Winfrey Show aired on KGTV in the same time slot.

The junk bonds were raised prior to Black Monday: by November 1987, Gillett recorded a 10:1 debt-to-profit ratio[119] and faced a $153 million loan payment by October 1989.

[92][120] Rumors of a sale ran hot in the lead-up to the conversion to News San Diego in 1988,[55]: 20  particularly as Gillett, who formerly had a role with the Miami Dolphins, expressed interest in buying the Seattle Seahawks.

[128] Facing lawsuits from multiple creditors including Apollo Partners, Allstate and Fidelity Investments, Gillett Holdings filed for Chapter 11 on July 26, 1991.

[131] Investor Ronald Perelman, regarded as a corporate raider and the owner of Revlon and Marvel Entertainment,[132] purchased majority control of SCI Television, including KNSD, on February 17, 1993,[133] pushing Gillett out entirely.

[134] The transaction came through a bankruptcy court-approved Chapter 11 reorganization: Perelman's holding company MacAndrews & Forbes made a $100 million investment in SCI, which was still burdened by $1.3 billion in debt, in exchange for 53 percent of its equity.

John Freeman of the San Diego Union-Tribune hypothesized that Fox wanted to keep XETV, one of its stronger affiliates and a VHF station, over KNSD.

Unsure of her employer's future, Denise Yamada left KNSD to anchor at KFMB-TV,[140] reportedly on the condition that she earn more money than her former co-anchor Levin.

[154] The first broadcast from 225 Broadway took place in December 2001, marking the first time downtown San Diego was home to a TV station since KFMB-TV left in 1977.

In December 2008, it canceled weekend morning newscasts, Noticias Mi San Diego (by then airing at 4 a.m. on KNSD itself), and Streetside as part of a layoff of 12 employees.

[169] For $9.6 million,[170] NBC purchased a 52,000-square-foot (4,800 m2)[171] building in Kearny Mesa—selected for its access to major roads and free parking[172]—which was gutted and rebuilt to provide newsroom, studio, and office space for the station and opened in 2016.