  We consider the symmetric teleparallel $f\left( Q\right) $-gravity in
Friedmann--Lema\^{\i}tre--Robertson--Walker cosmology with nonzero spatial
curvature. For a nonlinear $f\left( Q\right) $ model there exist always the
limit of General\ Relativity with or without the cosmological constant term.
The de Sitter solution is always provided by the theory and for the specific
models $f_{A}\left( Q\right) \simeq Q^{\frac{\alpha}{\alpha-1}}% ~,~f_{B}\left(
Q\right) \simeq Q+f_{1}Q^{\frac{\alpha}{\alpha-1}}$ and $f_{C}\left( Q\right)
\simeq Q+f_{1}Q\ln Q$ it was found to be the unique attractor. Consequently
small deviations from STGR can solve the flatness problem and lead to a de
Sitter expansion without introduce a cosmological constant term. This result is
different from that given by the power-law theories for the other two scalar of
the trinity of General Relativity. What makes the nonlinear symmetric
teleparallel theory to stand out are the new degree of freedom provided by the
connection defined in the non-coincidence frame which describes the nonzero
spatial curvature.
