People with a visitor role can perform this action only in the task and asset detail view.
Select an asset in the asset explorer. Now you have three options to upload a new version for the asset:
Via context menu: Right-click the asset to open its context menu and click "Upload new version" in the context menu.
Via featured action: Click the "Upload new version" action in the action area on the right side of the page.
Via magic menu: Select an asset and click the magic button in the action area. In the menu, click the "Upload new version" action.
Your file system's file chooser dialog opens.
Select an asset from your local file system and confirm your choice.
A new version of the asset is uploaded and the asset's preview in the asset list changes accordingly.
Select a folder in the tree so you see its assets in the asset list.
Open the asset detail view of an asset in asset explorer or in task details.
In the detail view, click the small button in the preview menu (above the preview area).
A new version for the asset is uploaded.
Click on a task to open its detail view.
In the task details, right-click an attached asset to open the context menu.
In the context menu, choose "Upload new version". A file chooser dialog opens.
Choose a file and confirm your choice.
When the upload is finished, the asset's preview image will show the new version.