in the voucher series per voucher type page:

hide the column period

select the financial year only and enter start from and until number values.

system will enter the value 99 in the hided period column.

I’m not sure what you mean. Now it looks like this. How can I do to only have 2022 in one row with one number series? Like 20220000 - 20229999

delete the unused records from period 3 to period 12.

hide column period

create new record , year=2022, from number , until number

save

system will use the new record for other periods.

Hi, Tobias
Please test approach suggested by @Nagah.khaled in test environment and let us know. 
I would be surprised if this solution is working. There is a checkbox on company “Use voucher number series per period”, I think it must be reset from TRUE to FALSE before you can define and use new number series. Which is normally not possible if transactions exist already. 

I’m using version 9; I checked the company page before posting my answer and I didn’t find the mentioned check box.

for the solution, I’m not sure it will work or not; it depend on the application behavior.

but even if it will not work there is no affect on the historical data because he will delete the unused records only.

thanks for your feedback.

I can’t untick this box since we have created postings. 
Also the solution suggested by Nagah doesn’t work. 

I think the only solution is a data repair. 

HI,

as long as you havn’t use the company you can or copy it and delete it and make the correct setup

or 

create a template, delete the old one and create a new one using the template and the correct setup

or

just create a new one and start from scratch (and delete the old one)

Regards

Ralph