How to set up the default time of data processing?

Go to Settings -> General settings and find the Consent valid for (in months) section.

24 months is the default value, but you can change that:

The validity time of specific consents depends on their type:

Consent type	Validity time
Particular recruitment consent	When creating this type of consent, you can choose: validity until the end of the recruitment validity for X months after the recruitment is closed This type of consent will not have an expiration date visible on the candidate profile.
Other recruitments consent	Validity set up in Settings, described above
Profiling	Validity set up in Settings, described above
Marketing consent	Validity set up in Settings, described above
Legal obligation	No validity date. The legal obligation is only information for the candidate about his personal data processing. This type of consent will not have an expiration date visible on the candidate profile.
Custom validity consent	Validity time is set up in this clause's settings (in months).