Does "alter" means "change into something worse"?

In French, the verb altérer means change into something worse or degrade. As a non-native English speaker I wonder whether the English verb alter has necessarily this negative meaning or in the contrary, if it is neutral as change or transform.

It is generally neutral.

• "Please alter your attitude." would mean to improve your attitude, by context.
• "I must remember to alter the path by which I drive to work every day."

Alter on its own has no positive or negative connotations. For example,

His character altered so much that I could not believe it was him

could mean he changed in a positive way, negative way, or simply a neutral way that made him very different from before.

The verb alter is often used to describe the process of making changes to clothing in order to improve the fit for a particular customer.

I wonder if native speakers of French avoid such businesses?