  We prove that the Kloosterman sum $S(1,1;c)$ can change sign infinitely often
as $c$ runs over squarefree moduli with at most 10 prime factors, which
improves the previous results of E. Fouvry and Ph. Michel, J. Sivak-Fischler
and K. Matom\"{a}ki, replacing 10 by 23, 18 and 15, respectively. The method
combines the Selberg sieve, equidistribution of Kloosterman sums and spectral
theory of automorphic forms.
