I have a spreadsheet with a data set containing `hours:minutes:seconds`. This dataset is a record of logged times per user (rows). The number of rows or columns isn't fixed. The number of columns is never fixed (constantly expanding for every new day logged). I want to create a new row based on the sum of each column. I assume I have to use ArrayFormula but I don't know where or how to approach. 

Rows are correlated to a number of users.

Columns are generated to a number of days logged.

Here is an example dataset: <https://docs.google.com/spreadsheets/d/1B05oOV8ZmcuHbm4v8iJLdZ6OAsO2ruEE4mOkv1PAPEk/edit?usp=sharing>

The formula should auto update the row with the sums of the new columns because it should be flexible enough to allow for new users/dates.

[![enter image description here](https://i.stack.imgur.com/M6tFf.png)](https://i.stack.imgur.com/M6tFf.png)