When applying for jobs and desired salary is asked for should I enter hourly or yearly pay?

Hourly or weekly is best. Some employers don't understand yearly.

I would say it often matters on the level of job, in the area of jobs I normally get pay is always discussed in yearly salary

In the jobs I get it's hourly pay that is discussed.

Again, it all depends on the position.

When in doubt you can always say "negotiable."