Security National Bank's assets at the end of 1982 increased to $167.6 million from $152.7 million in 1981. The figures were reversed yesterday.

Two Washington financial institutions, D.C. National Bank and Security National Bank, have announced leadership changes.

Robert P. Pincus has been named president and chief executive officer of D.C. National Bank, while Robert K. Koontz, vice chairman of Security National Bank and its parent company, Security National Corp., has retired, ending a 45-year career in banking in the District.

Koontz's retirement was announced by Security National chairman Leo M. Bernstein at the corporation's annual shareholders' meeting last Thursday.

He will be succeeded by Arthur A. Birney and Charles S. Bressler, who were elected vice chairmen by directors of the company at their meeting, which also was held Thursday.

Also elected to the board were Thomas J. Schaefer, president of the corporation and its subsidiary bank; Laurence W. Levine, John Manfuso Jr. and Morton H. Wilner.

Security National's deposits increased from $126.6 million at the end of 1981 to $142.5 million on Dec. 31, 1982. Assets at the end of 1982 totaled $152.7 million, compared with $167.6 million a year earlier.

At D.C. National Bank, Pincus succeeds Thomas S. Condit, who has resigned to pursue personal business interests.

Pincus, 36, began his banking career as a management trainee with D.C. National Bank's credit department in 1972. He was named a senior vice president in 1979 and executive vice president in 1982.

Pincus is a native of Washington. He graduated from the University of Maryland and earned a master's degree in business administration at American University.

D.C. National Bank, which is locally owned by the D.C. National Bancorp Inc., maintains assets of about $185 million and in 1982 reported income before securities transactions of about $2 million.