To convert a block, click on the ⋮ icon in the right margin and then under "Convert to", select the appropriate block (Paragraph, Decision, Task or Comment).
Info: In this example, a paragraph is converted into a decision, but the operation is the same for the conversion of other blocks. In order to save valuable time in your layout work, you can also convert most blocks.
Note that it is not possible to convert a Task into another block.