The dependence of the formation of ferroelastic stripe domain patternes on the thermal history is investigated be detailed piezoresponse force microscopy and X-ray diffraction expeiments after and during annealing of tensile strained tetragonal Pb(Ti,Zr)O3 epitaxial thin films on DyScO3 substates. In particular, the ferroelastic pattern is reversibly interchanged between a cross-hatched and a stripe domain patterne if the films are cooled at different rates after annealing above the formation temperature of a-domains. Different types of 180° and non-180° patterns can be created, depending on the thermal treatment. The changes in the 180° domain structure and lattice parameters are attributed to a change of oxygen vacancy concentration, which results in a modification of the internal electric fiels and unit cell size, causing also a shift of Tc. Thermal treatment is done on rhombohedral La:BiFeO3 thin films as well. It is observed that also in these films, appropriate heat treatment modifies the domain pattern and films with a stripe domain pattern can be created, confirming the general validity of the developed model.