my dps changes by itself

my dps has been constantly changing by itself seems like from hour to hour, i have no idea what my actual dps is now. i would like some help to know what to do

Can you give a bit more explanation about what is happening exactly? Do you mean the in game tool tip is going up and down? There may be variable on the build that change this number in game such as an aura. If you are in town your aura is not applied. That's one example of something, but there is a huge amount of things that apply to the tool tip that could be making the numbers vary. The exact answer will depend on your character.

Linking a POB or having your character viewable can be useful if you want more specific advice. You probably need to explain what is happening when the numbers are going up and down for someone to be more specific.

People often use POB for gauging their builds dps, as there are some things that the ingame tool tip doesn't take into account.

My dps would be 1100 at 12pm i log off and log back on 3pm and my dps is 800, it was changing by itself but i'm on a new character now, so i stopped caring.

There will be a different condition between the two states. Most likely one or more buffs were being applied to the calculation when it was at the high value, then not when the dps was at the lower value.

My bet would be that they logged out from their hideout or a combat area, so Auras were active. When they logged back in and ended up in town, their Auras were inactive, so their damage dropped.

I think that sounds likely.