Select the analysis options for Decomposition

Stat > Time Series > Decomposition > Options

Add a custom title or specify the first observation in the seasonal period.

Title

In Title, enter your own custom title to replace the default title.

First obs. is in seasonal period

Choose the time period in the seasonal pattern that the first observation occurs in. For example, if the seasonal pattern starts in January and the first observation is in June, enter 6. A value of 1 indicates that the first observation occurs at the beginning of the pattern.